Although noise of moderate intensity is commonly present during experiments on animal learning and memory, its effects have usually not been considered. The present study investigated how differences in the acoustic environment affect learning and memory under otherwise identical conditions. Genetically defined rats learned a complex maze in noise of moderate intensity (70 dB) or in quiet. Noise had a profound effect on learning and behaviour. Noise-exposed rats made fewer errors, explored less and finished their trials sooner. Results show that the acoustic environment is an important variable in studies with animal models of learning and memory. This might explain why differences in learning and behavioural scores occur across laboratories even when the same rodent strains and apparently identical experimental protocols are used. As the effects probably rely on neurotransmitter systems common in vertebrates, similar effects can be expected in other species including humans.