Seminal leukocytes are Good Samaritans for spermatozoa.

Objective: To assess the effect of leukocytospermia on assisted reproductive technology outcomes.

Design: Retrospective analysis.

Setting: University laboratory.

Seminal leukocytes and clinical outcomes with donor sperm insemination.

Objective: To report the level of leukocytospermia in fertile donors' semen. Surprisingly, seminal leukocytes protect fertilization properties of sperm and are associated with normal or improved assisted reproductive technology outcomes in infertility patients. This raises the question of whether leukocytospermia exists in fertile men as well.