The ultramorphologic sperm features of idiopathic infertile men after acupuncture therapy was investigated in a prospective controlled study. Forty men with idiopathic oligospermia, asthenospermia or teratozoospermia participated. Twenty eight of the patients received acupuncture twice a week over a period of 5 weeks. The samples from the treatment group were randomised with semen samples from the 12 men in the untreated control group. Quantitative analysis by transmission electron microscopy (TEM) was used to evaluate the samples, using a mathematical formula based on submicroscopic characteristics. Statistical evaluation of the TEM data showed a statistically significant increase after acupuncture in the percentage and number of sperm without ultrastructural defects in the total ejaculates. A statistically significant improvement was detected in acrosome position and shape, nuclear shape, axonemal pattern and shape, and accessory fibres of sperm organelles. However, specific sperm pathologies in the form of apoptosis, immaturity and necrosis showed no statistically significant changes between the control and treatment groups before and after treatment.