ABSTRACT. Spinelli M.O., da Cruz R.J., de Godoy C.M.S.C., Motta M.C. & Damy S.B. [Study of seasonal variation biochemical parameters of rodents and lagomorphs from the Vivarium of the Faculty of Medicine, University of São Paulo, São Paulo, Brazil.] Estudo da variação sazonal dos parâmetros bioquímicos de roedores e lagomorfos do biotério da Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brasil. Revista Brasileira de Medicina Veterinária, 36(2):219-225, 2014. Faculdade de Medicina, Divisão Técnica de Apoio ao Ensino e Pesquisa, Biotério Central, Avenida Doutor Arnaldo, 455, Cerqueira César, São Paulo, SP 01246-903, Brasil. E-mail: marilda@biot.fm.usp.br This work aimed to study the seasonal variation of the biochemical parameters of mice inbred BALB / c and C57BL / 6 mice, rats and rabbits New Zealand, the Vivarium of the Faculty of Medicine, University of Sao Paulo. Which is its clinical significance, assessing the analytes plasma ALT (alanine aminotransferase), AST (aspartate aminotransaminase), urea, urea-BUN (blood urea nitrogen), creatinine, total cholesterol and fractions VLDL (very low density lipoprotein), HDL (high density lipoprotein) and LDL (low density lipoprotein)? The results showed an increase in concentrations of analytes, statistical significance, especially in summer. The hypotheses that causes nutritional, infectious, water stress or climatic variations did not affect them, suggesting that to assess the health status of colonies of laboratory animals, biochemical parameters must be considered within the range of variation expected for each colony under study.