SOT 2023 -- Regulatory guidelines necessitate carcinogenicity studies to identify the tumorigenic potential in rodents and to assess the relevant risk in humans. The assessment of the intended chemical's ability to induce tumors in rodents helps with the prediction of the relevant risk in humans. Rodent carcinogenicity studies cover the entire lifespan of the animals with the evaluations including survival, body weight and clinical observations. A suitable rat strain for the carcinogenicity studies should be selected based on the predicted survival data for the entire duration of the study. Comparative data was collected from the historical data for Han� Wistar and Sprague Dawley� rats. To compare the performance of these two strains, survival, mass incidences, body weight, neoplastic incidences and motor disturbances were compared from the data compiled from multiple Labcorp Safety Assessment facilities.