Even though there is an abundance of information on the reference values of haematological parameters in adult rabbits, a little is known about the changes in haematology in newborn rabbits or during their postnatal development. Therefore, the aim of our study was to investigate changes in red blood cells (RBC), white blood cells (WBC) and differential leukocyte counts in SPF New Zealand White rabbits from the age of one day to 20 weeks. Significant age-related changes during the first four weeks of life were detected. These included an increase of RBC and WBC, reversal of the neutrophil/lymphocyte ratio and increase of total counts of eosinophils and basophils. From the age of six weeks of life, all of the studied haematological parameters were comparable to those of adult rabbits.