On the 36 cases with trichomonas vaginitis treated at our hospital (Okayama Saiseikai Hospital) by administering trichothamin (2-Acetylamino-5-nitrothiazoel) in a daily dosage of 300mg, 400mg, or 600mg, the authors followed up the results of the treatment by the droplet method and Papanicolaou's smears, and obtained the following results: Those temporarily cured only on the oral administration of trichothamin amounted to 84.2 per cent; those treated mainly with oral administration but combined it with suppository the cure rate was 88.8 per cent; and the rate of recurrent cases of those who had been followed up more than three weeks after the cessation of treatment was 50 per cent, namely, 9 cases out of 18 that had been followed up. The average total doses used was 7155mg in the cases cured, and 423mg in the cases who had recurrence. As for the side effect 30.5 per cent showed the side effects mainly consisting of the gastro-intestinal disturbances. However, the side effect was most noticeable in those given a daily dosage of 6CCmg, but those given the daily dosage of 300mg or 400mg showed only a slight side effect, and those receiving the drug in tablet form showed no side effect at all. Those treated continuously for a quite length of time hardly revealed any ill effect either. As for the treatment of the vaginitis by combination of oral and suppository administration, one tablet containing 50mg of trichothothiazole inserted into the vagina at the first call to the hospital has much more germicidal effect than the oral adminstration alone, and in addition, there is no side effect in evidence. In comparing the cured cases and recurrent cases and studying the amount and the method of administration of the drug in the treatment of recurrent cases, we consider that the daily dosage of 300mg or 400mg given continuously until the total amount reaches about 7,000mg will yield the result and that the spouse should also be treated concurrently in order to obtain a better result.