The hematological and biochemical parameters of 140 apparently healthy sheep consisting of 70 adults (35male and 35 female) comprised of 3 indigenous and popular brzzeeds of sheep of northern Nigeria were studied. Data were analyzed for the effect of breed, sex and season packed cell volume (PCV) was significantly higher (P<0.05) for Ouda ram of the north west. Haemoglobin (Hb) values was higher (P<0.05) for Balami sheep. Red blood cell count (RBC) was significantly (P<0.05) for Balami ewes. The mean corpuscular hemoglobin (MCH) was higher in Balami ram (17.89 Pg) while the values were much higher in Yankasa ewe lamb. The mean corpuscular hemoglobin concentration (MCHC) was significantly higher (P<0.05) for adult sheep than in lambs. The mean corpuscular volume (MCV) was observed to be higher for Ouda ram (98.8 fl) while the values were much higher in Yankasa ram lamb. Yankasa ewe had the highest white blood cell count (WBC). White blood cell differential shows that lymphocytes was significantly higher (P<0.05) for Yankasa sheep (adult). Neutrophils was significantly higher (P<0.05) for Balami ewe (adults and lambs). Eosinophils was observed only in Yanksa goats (adult and lamb). Monocytes was observed only in Ouda ram. The serum sodium ranged from (140.0 to 156.0 mmol/l) for adult sheep of all breeds, (140.0 to 160.0 mmol/l) for sheep lambs of all breeds. Serum potassium ranged from (4.60 to 12.4 mmol/l) for adult sheep (4.70 to 13.70 mmol/l) for sheep lamb. The chloride and HCO- 3 values was higher for sheep lambs than in adults for all the breeds, values for urea, creatinine, glucose, total protein, cholesterol, globulin and albumin was observed to be higher for adults sheep than in lambs. The enzymes Asparttate Aminotranferase (ASP) and Alanine aminotransferase (ALT) were significantly (P<0.05) higherin Ouda sheep (adults and lambs).