P. K. Das , M. Mostofa , Q. Hasan , G. C. Shil , M. R. Islam , Effects of Ranitidine, Famotidine and Omeprazole on Some Haematobiochemical Parameters in Mice, Journal of Animal and Veterinary Advances, Volume 2,Issue 6, 2003, Pages 321-326, ISSN 1680-5593, javaa.2003.321.326, (https://makhillpublications.co/view-article.php?doi=javaa.2003.321.326) Abstract: The research work has conducted in 4 groups (each containing of 5 mice) of swiss albino mice following oral administration of H2-blockers and proton pump inhibitor (Ranitidine, Famotidine and Omeprazole) at the dose rate of 100 mgkg-1. b. wt. 13.33 mgkg-1. b. wt. and 3.33 mgkg-1 b. wt., respectively to investigate the toxic as well as gross pathological changes and also to estimate the blood glucose level. Loose faeces were found in group B (Ranitidine) during last few days of experimental period. Following post-mortem examination, congestion and pale colour of the liver was found in group C and D respectively. In the treatment group B (Ranitidine), TEC, TLC, Hb%, Monocyte, Neutrophil and Eosinophil count were significantly decreased whereas Lymphocyte was significantly increased in the same treatment group. The highest decrease in TEC (16.08%), TLC (17.77%), Hb% (20.75%), Monocyte (33.33%), Neutrophil (26.31%), Eosinophil (33.33%) was recorded. In the treatment group C (Famotidine), TLC, Monocyte count, blood level serum were significantly decrease whereas Lymphocyte count was significantly increased in the same treatment group. The highest decrease of TLC (17.41%), blood glucose (36.67%), Monocyte count (41.66%) was recorded. The highest increase of Lymphocyte was also recorded. In the treatment group D (Omeprazole), TLC, Monocyte count, blood glucose level were significantly decreased whereas Lymphocyte and neutrophil count was significantly increased. The highest decrease of TLC (23.28%) and Monocyte count was also recorded. Keywords: