Dunedin had a commanding win at Hancock Park because its forwards won the battle in the loose and the backs ran straight up the field.
The Pirates forwards were a competitive unit but inept handling and across-the-field running by the backs let the team down.
Dunedin led 12-8 at the break but it took another 15 minutes for it to break through a stubborn Pirates defence, score another try and crack the game open.
Dunedin scored four tries and 26 unanswered points in the last 25 minutes.
Loose forwards Scott McKee and John Crossan were aggressive at the breakdown for Dunedin, playing key roles in the game.
Lock Tom Crowley was accurate in the line-out and mobile about the paddock.
The backline made good use of second-phase possession and ran hard up the centre to test the defence before feeding the ball out wide to fullback Louis Tili and winger Tumua Ioane, who scored three of the six tries between them.
Flanker Josh Clark was the only Pirates player to enhance his reputation.
Dunedin 38 (Tumua Ioane 2, Louis Tili, Fraser Lau, Robbie Smith, Shaan Davis tries; Tili 3 conversions, Josh Hamilton conversion),
Pirates 8 (Josh Clark try; Andrew Bremner penalty goal).
Half-time: Dunedin 12-8.
Referee: Jeff Grubb.
