O'Gara started the game and from Pez's clearance Ireland lost the first lineout. They won the next one but turned over the ball to allow Kaine Robertson chase a chip ahead over the Irish line.Italy then suffered an early blow when they lost Mauricio Zaffiri to injury and when they went offside moments later O'Gara opened Ireland's account with a well struck penalty.
Italy enjoyed their best period just after that and it started with Robertson dancing away from would be Irish tackles on the right and ended with an 11th minute Ramiro Pez drop-goal.
Two minutes later when Italy went long from a line-out Simon Easterby was the recipient but was penalised for not releasing in the tackle and Pez kicked Italy into the lead.
It was a lead that didn't last very long because D'Arcy's half break released Denis Hickie who found his captain and O'Driscoll gave the scoring pass to Girvan Dempsey.
A 25th minute Pez penalty closed the gap (13-9) but after Brian O'Driscoll was penalised for holding on the Italian 22, Pez booted Italy to the Irish 22 and from the line-out Pez landed his second drop-goal. (13-12).
A 33rd minute penalty allowed O'Gara gain a lineout inside the Italian 22 but they failed to win that and were penalised at the subsequent scrum to let Italy raise the siege. Obstruction at the next phase gave Pez the opportunity to put his side ahead but his kick from the half way drifted wide.
Then D'Arcy scored Ireland's third try although the pass from Hickie looked clearly forward but O'Gara tapped over the conversion and Ireland led 20-12.
Italy lost Pez through injury at half-time and Ireland were under pressure in the opening minutes of the second half but once again an Italian error when they looked threatening allowed Hickie take play right down to the other end and Dempsey scored his second try in the 45th minute benefiting from a sublime inside pass from O'Gara.
From then on Italy were under all sorts of pressure and a delightful O'Gara chip almost put O'Driscoll in under the posts. Moments later a sublime Ireland move ended with Horgan crossing and Ireland went twenty points clear (32-12).
Hickie was next over as the Italians crumbled under the weight of superb Irish play and O'Gara's conversion made it 39-12 with the Italians in total disarray.
Another promising Italian attack ended with an Irish score for Ireland when D'Arcy broke clear from deep inside his own 22, support came from O'Driscoll and O'Gara finished it off but again there was a forward pass before the out-half touched down.
To their credit Italy recovered somewhat and an Andrea Scanavacca cross-field kick was gathered by Marco Bortolami over Hickie's head to score a 75th minute try. The Leinster wing compensated moments later with a try to give Ireland a 51-17 lead.
A little over two minutes into injury time Ronald De Marigny scrambled over and after Kaplan went 'upstairs' the try was awarded and Scanavacca converted.
Ireland: Girvan Dempsey; Shane Horgan, Brian O'Driscoll (Andrew Trimble 60th min), Gordon D'Arcy, Denis Hickie; Ronan O'Gara, Peter Stringer; Marcus Horan (Simon Best 65th min), Rory Best (Jerry Flannery 61st min), John Hayes; Donncha O'Callaghan, Mick O'Driscoll (Trevor Hogan 53rd min); Simon Easterby, David Wallace, Denis Leamy.
Italy: Roland De Marigny; Kaine Robertson, Ezio Galon (Matteo Barbini 63rd min), Mirco Bergamasco, Matteo Pratichetti; Ramiro Pez (Andrea Scanavacca ht), Alessandro Troncon (Paul Griffen 80th min); Salvatore Perugini (Fabio Staibano 54th min), Carlo Festuccia (Ghiraldini 80th min), Carlos Nieto (Perugini 68th min); Santiago Dellapè, Marco Bortolami; Alessandro Zanni, Maurizio Zaffiri (Josh Sole 2nd min), Sergio Parisse (Valerio Bernabo 67th min).
Referee: Jonathan Kaplan (South Africa).