Uterine infections, particularly myometritis have been shown to be severe because of the difficult passage of the antibiotics into the affected tissues. Consequently, a biochemically novel drug, cefotiam (CTM) was investigated for the distribution into the uterine body, uterine cervix, ovary and oviduct of 10 patients with benign tumor, 1 g of CTM in 250 ml of 5% glucose was infused for 2 hours. The mean concentration of the antibiotics in the serum, uterine body, uterine cervix, ovary and oviduct at 30 minutes after the intravenous drip infusion was, respectively 19.7 micrograms/ml, 10.1 micrograms/g, 12.9 micrograms/g, 10.7 micrograms/g and 11.7 micrograms/g. The concentration ratio of the tissue to serum was found to be relatively high (51.5--65.5%), as compared to other antibiotics. In this experiments, no adverse effects, such as laboratory findings were found.