The French club, runners-up in the competition last year, suffered a surprise 28-27 defeat to the Italian side six days ago to open up Pool Four but a repeat never looked on the cards as a 10th-minute try from centre Marcelo Bosch and a penalty try 12 minutes later — both converted by France scrum-half Dimitri Yachvili saw the hosts storm into a 20-0 half-time lead.
Wing Taku Ngwenya and hooker Benoit August also crossed for tries after the interval, with Yachvili adding the extras, before Aironi fly-half Riccardo Bocchino at least got his team on the scoresheet with a penalty on the hour.
Biarritz scorers: Tries: Bosch, Penalty, Ngwenya, August. Cons: Yachvili 4. Pens: Yachvili 2.
Aironi Rugby: Pens: Bocchino.
BIARRITZ: Haylett-Petty, Ngwenya, Bosch, Traille, Balshaw, Peyrelongue, Yachvili, Watremez, August, Johnstone, Thion, E. Lund, M. Lund, Vahafolau, Harinordoquy.
Replacements: Mignardi for Bosch (72), Bolakoro for Balshaw (67), Tranier for Peyrelongue (64), Guinazu for Watremez (51), Terrain for August (64), Taele-Pvihi for Thion (51), Lauret for Harinordoquy (67).
AIRONI RUGBY: Laharrague, Toniolatti, Pratichetti, Pizarro, Rubini, Bocchino, Canavosio, Perugini, Ferraro, Staibano, Bortolami, Geldenhuys, Liebenberg, Favaro, Erasmus. Replacements: Marshall for Laharrague (70), Venditti for Toniolatti (64), Wilson for Canavosio (64), Santamaria for Ferraro (53), Gamboa for Staibano (53), Krause for Liebenberg (53).
Ref: Andrew Small (RFU).