1. 1. Hematological parameters in the male and female bats differ only with respect to number and volume of erythrocytes: larger number of smaller cells found in males corresponds to smaller number of larger red blood cells in females, with hemoglobin level and hematocrit values remaining similar in both sexes. 2. 2. Six-month-old bats have significantly higher numbers of lymphocytes when compared with adults. 3. 3. There are no significant differences in hemograms (complete blood counts) for bats identified as “ nathalinae” and “typical” Myotis daubentoni.