The efficiency of medroxyprogesterone acetate (MAP) and fluorogestone acetate (FGA) sponges for synchronizing oestrus in lactating Saanen goats was investigated during the transition from non-breeding to natural breeding season. Does were treated for I I days with 60 mg MAP (n=19) or 40 mg FGA (n=24) sponges. All does received intramuscular injections of 750 IU pregnant mare serum gonadotrophin (PMSG) and 125 mug cloprostenol (PGF(2)alpha) 48 h prior to sponge removal. Cervical artificial insemination (AI) with fresh diluted semen was performed at a fixed time (36 and 48 h) followed progestagen withdrawal. The two progestagen treatments showed no significant difference in oestrous response (100% both for MAP and FGA groups), time to the onset (15.8 +/- 09 and 15.0 +/- 06 h for the MAP and FGA groups, respectively), duration (30.5 +/- 1.9 and 34.0 +/- 1.4 h for MAP and FGA, respectively) and cessation (42.32 +/- 1.6 and 43.25 +/- 1.3 h for MAP and FGA, respectively) of the induced oestrus period. No significant difference was observed with respect to pregnancy rates determined at the 53(rd) day after AI (52.6 and 50.0% for MAP and FGA, respectively). These dates indicate that the use of MAP and FGA intravaginal progestagen treatments are equally efficient in synchronizing oestrus in lactating goats during the transition from the non-breeding to the natural breeding season.