Haematology of reptiles is a field that began to develop and explore in recent decades due the growing number of reptiles that are kept as pets, and thus are more common as patients in veterinary practices. Making blood count in reptiles is a process which is not yet working in clinical veterinary practice, but as we learn about ways of determining hematology and hematological parameters in reptiles we make a oportunity for veterinarians of small practices to routinely determine haemogram of the reptiles. All haematological parameters are determined manually, and so to obtain a complete blood count, other than expertise and experience of the person who made haemogram, it is necessary to have laboratory equipment and reagents. All blood cells of reptiles have a nucleus so during cell differentiation we should be cautious and we have to prevent the replacement of certain types of cells. Numerous external and internal factors have an affect on the number and morphology of blood cells of reptiles and that should be kept in mind while interpreting the findings. Change in the number and morphology of blood cells during various diseases and pathological conditions are occuring depending on the type of reptiles, severity and duration of illness.