Different non-specific immune parameters and their seasonal changes in brood Indian major carp Labeo rohita reared in two major freshwater aquaculture regions of India viz. West Bengal and Orissa were investigated. It was undertaken for 2 consecutive years and included three main seasons of a year such as summer (March-May), rainy (July-September) and winter (November-January). Total serum protein, albumin and globulin levels were not significantly different throughout the year (p>0.01). Serum lysozyme and myeloperoxidase activities were lower (7.26+/-0.87mg/ml and, 0.54+/-0.11 OD, respectively) in winter as compared to any other season of the year. The bacterial agglutination titer was higher (p<0.01) in the rainy season (8.70+/-1.70) compared to summer and winter seasons (3.40+/-0.60 and 4.00+/-0.89, respectively). Haemagglutination and haemolytic activities did not vary (p>0.01) throughout the year. In blood smears, lymphocyte percentage was higher (75-80%) as compared to those of neutrophil (10-15%) and monocytes (5-10%) but eosinophilic granulocytes were present only in few cases. The differential leucocyte count did not vary significantly (p>0.05) in any season. This study indicated that certain non-specific immune parameters of this species can be modulated at certain times of the year.