The aim of this prospective controlled study was to assess the effect of acupuncture on the sperm quality of males suffering from subfertility related to sperm impairment. Semen samples of 16 acupuncture-treated subfertile patients were analyzed before and 1 month after treatment (twice a week for 5 weeks). In parallel, semen samples of 16 control untreated subfertile males were examined. Two specimens were taken from the control group at an interval of 2-8 months. The expanded semen analysis included routine and ultramorphological observations. The fertility index increased significantly (p < or = .05) following improvement in total functional sperm fraction, percentage of viability, total motile spermatozoa per ejaculate, and integrity of the axonema (p < or = .05), which occurred upon treatment. The intactness of axonema and sperm motility were highly correlated (corr. = .50, p < or = .05). Thus, patients exhibiting a low fertility potential due to reduced sperm activity may benefit from acupuncture treatment.