Nitrate can cause multiple physiological effects if allowed to build up to high concentrations in animals. This work is concerned with the study of short term (14 days oral intoxication) nitrate exposure to male and female Charles foster rats that were divided into 4 groups. Ist group was allowed free access to distilled water whereas IInd, IIIrd and IVth groups were provided with water possessing nitrate concentration 45 mgL-1 , 90 mgL-1 and 135 mgL-1 NO3 – respectively. Under these conditions the haematological parameters such as T-RBC count, Hct and Hb showed increasing trend while TLC and blood platelets showed decrease in response to the stress imposed. Certain variations were observed in differential leucocytes count. Nitrate contaminated water seems to have disturbed the physiology and metabolism of experimental mammals (rats).