Previous work has suggested an association between male subfertility and a female-biased offspring sex ratio. This study of the reproduction of men who had a semen analysis at the Sperm Analysis Laboratory in Copenhagen in the period 1963-1993 showed that the subfertile men had an offspring sex ratio as expected (51.0% boys versus 51.3%, P: = 0.56), and within the cohort, the offspring sex ratio had no material association with particular semen characteristics. Our results thus suggest that no important association exists between general male subfertility and a female-biased offspring sex ratio.