The effect of short-term (3 h) exposure to 10 mg/l of Pb (96hLC50) on common carp hematological parameters was evaluated every 2 days for 16 days post exposure. Fluctuations of the values of red blood parameters were observed over the entire experimental period. Increase in frequency of morphological anomalies in erythrocytes also occurred and no complete recovery took place until the end of the experiment. Chromatin condensation at the nucleus border and nuclear malformation were the most common anomalies and seem the most pronounced hematological alterations induced by lead in carp. In first days post exposure a decrease in immature neutrophil percentage, followed by a drop in mature cell frequency, accompanied by a decrease in phagocyte activity occurred. This was followed by a transient but significant decrease in leukocyte count 8 days after the end of exposure. A persistent decrease in basophil frequency was observed until 8 days post exposure. The observed changes suggest that lead disturbed nonspecific immune responses in carp.