This review assesses whether human follicular fluid (hFF) is able to modify human sperm function in vitro. Addition of hFF has been found to stimulate the motility of washed human spermatozoa, to increase the percentage of hyperactivated spermatozoa, to induce the acrosome reaction, to attract spermatozoa to the site of fertilization and to facilitate penetration of the oocyte by spermatozoa. It is possible that hFF could provide a favourable environment around the oocyte for fertilization by spermatozoa. Inclusion of hFF in gamete transfer medium may also improve the success rate of assisted reproduction technology. Purification of individual components in hFF which modify different aspects of sperm function awaits further investigation.