Examining blood level values and urinary concentrations taken from pregnant and nonpregnant women, the pharmacokinetic dates of azlocillin have been evaluated. We used a computer program based on the two-compartment model. The evaluation of azlocillin concentrations in serum and urine has been realized with the two following methods: polarography and agar diffusion test. We found nearly equal values of serum concentrations when using both methods. There are no statistical differences between pharmacokinetic dates of pregnant and nonpregnant women. Therefore we state: It is not necessary to change the dosage and the application interval of azlocillin during pregnancy.