Separate groups of male and female B6C3F1 mice were administered chlorine and monochloramine in drinking water for 90 consecutive days. Both disinfectants were supplied at 12.5, 25, 50, 100 and 200 mg/L. Criteria evaluated included mortality, clinical signs, body weight, food consumption, hematology, clinical chemistry, organ weights, gross pathology, and histopathology. Overall, the correlation of the biochemical, hematological, and organ weight data, in the absence of histopathology and observable clinical signs of toxicity, suggests that the chlorine and monochloramine induced effects via an indirect mechanism, e.g., nutritional deficiencies, rather than a direct toxicological effect on specific organs or tissues. Includes 32 references, tables.