The authors have carried out the laboratory and clinical studies of cefamandole (CMD). The results are as follows: The sensitivity was measured by plate dilution method on 26 strains of Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and 14 strains of Salmonella typhimurium isolated from patients. The distribution of sensitivity of S. aureus was 0.39 approximately 3.13 micrograms/ml and the peak of distribution was 1.56 micrograms/ml. The distribution of sensitivity of E. coli was 0.78 approximately greater than 100 micrograms/ml, and K. pneumoniae, 1.56 approximately greater than 100 micrograms/ml. The distribution of sensitivity of Salmonella typhimurium was 6.25 approximately greater than 100 micrograms/ml and its peak was 6.25 micrograms/ml. CMD were given intravenously for 30 and 60 minutes at a single dose of 25 mg/kg body weight to 6 children. The serum mean levels of CMD were 105.3 micrograms/ml at 30 minutes, 15.1 micrograms/ml at 1.5 hours, 1.6 micrograms/ml at 2.5 hours after drip infusion for 30 minutes, respectively, and 34.7, 5.2, 0.6 micrograms/ml at 1, 2, 3 hours after drip infusion for 60 minutes, respectively. And the serum level at 4 hours after administration was not detected. The mean urinary excretion rates were 73.3% in the drip infusion for 30 minutes and 60.7% in its for 60 minutes, up to 8 hours after administration. Half life was 26 minutes. CMD was effective in 18 of 21 cases of bacterial infections. No side effects were observed except for 2 cases with elevation of serum transaminase.