Anyone who watched Patrick O'Reilly's towering, fibre-glass sculpture of the hurler, D.J. Carey, being carried through the streets at last year's Kilkenny Arts Festival will not be surprised by the artist's latest collaboration with Macnas: The Lost Days of Ollie Deasy. The Ollie Deasy character is a former hurling hero who goes off to play an exhibition match at some point in the 1960s and disappears. This hurling theme that's emerging in O'Reilly's work - is it something to do with his Kilkenny background? "I've always thought that it's a beautiful sport," says O'Reilly, "and D.J. Carey was a master. You have to acknowledge the sheer skill of it, when you see teams like, well - Kilkenny . . ."

There may have been plenty of hurling in Ballyragget, Co Kilkenny, when O'Reilly was growing up there in the 1960s, but there certainly wasn't much art. "Coming from a small country village, I had a lot of guilt about `wasting my life' at something like art. I didn't know anyone else who shared my interest and I don't know where it came from. I had the burning desire to make work since childhood, but I never believed I could do anything of merit. I lacked confidence and absorbed the sense that somehow I was just indulging myself." Listening to him now as he sits sipping wine and surveying his garden in Dublin, having just returned from an exhibition opening at the Hague, this urbane, enormously successful, 43-year-old artist seems to have travelled a long way from his younger self.

Since he first burst onto the art scene with an exciting solo show of installations at Galway Arts Festival in 1996, O'Reilly has not paused for breath. His small bronzes, huge, quirky, fibre-glass figures and kinetic, sculptural installations have been exhibited from Florida to Maastricht, and he has created exuberant public sculptures for O'Connell Street (Bird) and Thomas Street (the 50-foot Rocket) in Dublin. His work eludes neat categorisation, but comes under the general heading of "Expressionism", full of humour and fantasy. Beneath the apparent playfulness, however, his elaborate installations often take a wryly sympathetic view of fragile human lives, of people in pain. A didactic work such as Mop- ping Up, which evokes the condition of depression, has a poignant undertow which manages to avoid sentimentality.

In four hectic years O'Reilly has had one-man shows at London's Mayor Gallery, the Galerie Kyra in Berlin and Gallery Pilitzer in Paris, as well as Dublin's Hugh Lane and Solomon Galleries. The current group show Hague, in which one of O'Reilly's figures shared the billing with a Rodin and a Giacometti, first opened in the 18th-century elegance of the Palais Royal in Paris earlier this year. "From Galway to the Louvre does seem quite a leap," he laughs.

He speaks passionately about the need for Irish visual artists to be promoted more vigorously abroad, and for young Irish artists and art students to look beyond the London art world and its preoccupation with Saatchi-style hype. "I'm lucky. I've discovered that my work gets a huge response in Europe - and they have the money there to buy it, even the really big pieces. They're not afraid of it. I suppose they have been looking at new art for longer. They're open to the unusual."

O'Reilly's prolific rate of creativity over the past four years isn't anything new, he says. It's just that now he has confidence, and knows he can make a living from doing what he loves. "Isn't that a privilege?" So what about the long gap between leaving art college in Belfast in the late 1970s and the Galway debut? Were these the lost years of Patrick O'Reilly? "Far from it. People always assume that my first Galway show came out of the blue, but that was a lifetime's work. I was working all the time by myself, for the joy of it, while I earned my living in the furniture business. The art was a drug, a compulsion, but I became very vulnerable about it. I felt sure that people would dislike it and as long as I didn't show it, I could live in the vague hope that it had some merit. The Galway show changed all that, because I realised that people did like it."

After that exhibition, Macnas, in the form of Paraic Breathnach, realised that this was an artist whose inventiveness and energy could harmonise with the company's spirit. O'Reilly was invited to propose an idea for a theatre production, which he would design. The result, with the help of writer Mary Drechsler, was the ambitious but flawed ensemble piece, Diamonds in the Soil, based on the life and work of Vincent Van Gogh. Mikel Murfi of Barabbas directed the production, which premiered at the Dublin Theatre Festival two years ago. Director and designer are now reunited for The Lost Days of Ollie Deasy, but this time the script and concept are Mikel Murfi's. "It's a version of The Odyssey, with the audience boarding a bus and going off on the trail of the missing Ollie Deasy. The map of Odysseus's wanderings around Greece is superimposed on the map of Ireland, so we're taking them on a visual, imaginary journey through Ireland."

With cultural references to Corpus Christi processions, Artane Boys Bands and feilte, is this going to be a nostalgia trip? "The imagery is going to be real and raw rather than rose-tinted," O'Reilly says. "Mikel and I know the world we're evoking, so it won't be a view of rural Ireland from London or New York. It's not so far from reality that it will alienate people."

For O'Reilly, working with Macnas doesn't require a huge change of gear. "It's a bit of a tangent, but it's fun. I'm attracted by the openness of Macnas, the free spirit. They make mistakes, or they fail, but they don't compromise. They are going through a period of flux, certainly, but the challenge for the company is to stay on the edge.

"Everything with Macnas is a collaboration - I make the drawings or models, which are the raw material, but by the time Pete Nelson and his team have worked on them, and built the sets, the recognisable Macnas look has been created. I'm really a minor player." In the world of theatre, perhaps.

The Lost Days of Ollie Deasy runs at Leisureland from Wednesday, July 19th, until Sunday July 30th at 8 p.m.