Carlow dominated a lethargic Lansdowne side until the final 15 minutes when the Dublin side hit back with a brace of converted tries to come within a converted try of the home side.
At that stage with nine minutes to play Carlow led 27-20 but justice was served when the home outhalf Billy Murphy kicked a splendid penalty for 40 metres after a Lansdowne back failed to release.
Carlow deservedly led 13-3 at halftime. They picked up a bonus point for their four-try haul
CO CARLOW: M Spiller; M Buckley, P Jones, R Armstrong, I Dwyer; B Murphy, R Jones; P Brennan, J Hannon, L Hannon, L O'Byrne, R Bolger, B Baggott, D Hyland, A Melville. Replacements: D Cox for Baggott (54 mins). P Holden for O'Byrne (57), M Waterhouse for Buckley (69).
Lansdowne: E Doherty; R Dolan, L O'Brien, D P O'Mahony, F Baynes; A McGowan, S Whelan;E Behan, R Fallon, C McMahon, S O'Connor, G Quinn, S Rooney, L Toland, A McCullen, Replacements: K Becker for Whelan (inj 52 mins). G Fulcher for O'Connor (57), B Geraghty for Dolan 59 mins.
Referee: L Mayne (Munster)