Bacterial vaginosis (BV) is the most common cause of vaginal discharge in women of childbearing age. In some women it shows a relapsing and remitting course with apparently spontaneous onset and resolution. There are intermediate patterns of vaginal flora in which lactobacilli and other species co-exist. We asked women with recurrent BV to prepare vaginal smears daily, and to record symptoms, time of menstruation, sexual activity and use of douches or medication. We Gram-stained the smears and assigned a Nugent score for BV, and noted the presence of candida, pus cells, sperm and blood. Eighteen women collected daily vaginal smears for up to 10 months. Forty months of slides were collected in total. Bacterial vaginosis arose spontaneously on 23 occasions. We saw candida arise 11 times. Bacterial vaginosis appeared after candida on 9 of these 11 episodes. We saw BV regress spontaneously 13 times. Nine of these resolutions occurred within 48 h of unprotected sexual intercourse: BV only arose on one occasion within 48 h of unprotected intercourse. The intermediate pattern was seen for up to 10 days, and occurred as BV began or resolved in some women, and sometimes resolved without developing into BV. Bacterial vaginosis arose most often in the first 7 days of a menstrual cycle, and resolved spontaneously most often in mid-cycle. In women with recurrent BV, BV arises most often around the time of menstruation and resolves spontaneously in mid-cycle. Recurrences often follow an episode of candidiasis, and BV often regresses after unprotected sexual intercourse.