A comparison of 5 commercial mosquito repellents was made on adult male and female volunteers in laboratory trials. The products tested in forms of cream or lotion included 4 natural oil formulations (containing citronella, clover, eucalyptus, geranium, lavender, peppermint, sandalwood, thyme, etc.) and 1 synthetic chemical repellent containing 10% KBR 3023). Natural oil products showed essentially poor or no repellency against Ae, aegypti: the protection times were less than or equal to 1 hour. Only the synthetic repellent based on KBR 3023 provided satisfactory defence to human volunteers.