In this [corrected] study, we purified hcbCA I and II from human cord blood erythrocytes using [corrected] Sepharose-4B-l [corrected] tyrosine-sulfanilamide affinity gel chromatography. [corrected]. The inhibition effects of ampicillin sulfate, ceftriaxone, ceftizoxime and ranitidine on hcbCA I and hcbCA II were also monitored. [corrected]. IC(50) values for ceftriaxone, ceftizoxime and ranitidine were found to be 27.l, 79.4 and 55.5 µM, respectively, [corrected] for hcbCA I, and [corrected] 21.0, 79.1 and 66.1 µM, respectively, [corrected] for hcbCA II. [corrected]. According to these results, ampicillin [corrected] sulfate inhibited only hcbCAII and IC(50) value [corrected] of this antibiotic was found to be 56.8 µM. All [corrected] substances were found to be [corrected] non-competitive inhibitors. It is important to study the inhibition effects of these drugs on hcbCA I and II izoenzymes as pregnant women are often prescribed these antibiotics. [corrected]. For this reason, the dosage of [corrected] these drugs should be carefully evaluated [corrected] to minimize side effects.