Triethyltin is an organotin compound which is known to produce neurotoxicity in both adult and developing organisms. The present study reports four experiments that examined this question with an odor aversion learning paradigm in which pups receive presentations of one odor paired with footshock and an alternate odor without shock. In Experiment 1, Long-Evans rat pups were injected i.p. on postnatal day 5 (PND5) with either 0, 3 or 5 mg/kg TET and then tested for olfactory discrimination learning on PND18. Only the 5 mg/kg dose impaired discrimination learning. In Experiment 2, PND5 exposure to TET (5 mg/kg) disrupted olfactory learning on PND18 but not on PND12 whereas exposure on PND10 disrupted learning at both ages of testing. In Experiment 3, PND16 exposure to TET (5 mg/kg) also disrupted acquisition of olfactory learning on PND18 but had no effect on retention of an olfactory discrimination that was acquired prior to TET exposure (ie. on PND14 and PND15). Unconditioned responses to footshock were also unaffected by TET (Experiment 4). These findings indicate that neonatal exposure to TET impairs associative learning in developing rats and are discussed in relation to other studies of the developmental neurotoxicity of this compound.