Investigation on the prevalence of blood-parasites in the hyperthermic pet dogs of Kathmandu Valley was carried out from September 2009 to December 2009. A total of 50 blood samples were collected from different clinics and hospitals of Kathmandu Valley and tested for blood parasites. The RBC, WBC, PCV, Hb, DLC of each sample were also assessed and analyzed. Data was analyzed to determine prevalence of various species of blood parasites to establish the correlation of these infections with age, sex and breed. An overall prevalence of blood-parasites was recorded as 14 %; Babesia canis, B. gibsoni and Ehrlichia spp being 8. 00%, 2. 00% and 4. 00 % respectively. The percentage of infection was greater in males (12%) than females (2%). High occurrence was encountered in German shepherd breed of dog (85. 71%) and rest (14. 29%) was found in Japanese Spitz. The prevalence of blood parasites was found to be greater in the higher age group of canine population.