We investigated the direct effects of bromocriptine on the motility of the human ejaculated spermatozoa and its capacity to penetrate the cervical mucus (CM) in vitro. Washed sperm were incubated with a wide range of bromocriptine concentrations (0.005 to 5 mM). Progressive and total motility was evaluated after 15, 30, 60, and 180 minutes. No reduction of motility was observed at any concentration tested. Similar results were observed with semen samples. Failure to alter sperm motility was evident in samples with either good or reduced motility. Also, CM penetration as measured after 90 minutes by Penetrak assay (Serono Diagnostics, Randolph, MA) was not impaired by a concentration as high as 5 mM bromocriptine. We conclude that bromocriptine in a wide range of concentrations does not inhibit sperm motility nor does it impair the capability of the sperm to penetrate the CM. These data support the therapeutic use of daily vaginal bromocriptine for the treatment of infertility.