One thousand six hundred forty-one IUI cycles performed in 615 couples were categorized, depending on the semen analysis of the male partner, in three groups of: normozoospermia, teratozoospermia, and male factor infertility. Clinical pregnancies and live births per cycle were significantly decreased in the teratozoospermia group when compared to the normozoospermia group, with the exception of the first IUI attempt (comparable outcomes), whereas the cumulative live birth rate after four IUI attempts was significantly lower in the teratozoospermia and male factor infertility groups.