ABSTRACTSterility is relatively rare in exhibition budgerigars, but it does occur. In this study infertility in males resulted from abnormal or absent sperm production and abnormal sexual behaviour. The latter was also found in infertile hens, together with hernias altering the cloacal anatomy, infections and cysts of the oviduct and deformed ovarian follicles. Infertility was also commonly associated with the presence of disease outside the reproductive system in both sexes.