In this paper pharmacokinetic data of acylureidopenicillins (azlocillin and piperacillin) in pregnant women in the last trimenon are compared with those from nonpregnant controls. Four g of each drug was administered as slow bolus injection intravenously. The concentrations in serum and urine of both drugs were determined by polarographic and microbiological methods, for comparison. We used for evaluation of pharmacokinetic data a computer program based on the equations of a two-compartment open pharmacokinetic model. Our investigations show that there are not any different pharmacokinetic values of both antibiotics between pregnant women and healthy nonpregnant volunteers. We can state that both antibiotics are well determined by both analyzing methods which give us identical pharmacokinetic results.