It is known that sodium nitrite and dimethylamine are toxic compounds, which may react to form dimethylnitrosamine in the gastro-intestinal tract, a much more toxic compound and a powerful cancerogen. The aim of the present work is the investigation of toxicity in young rats, caused by daily intake of sodium nitrite, administered together with dimethylamine during 30 days. The indicators examined were: histopathological analysis of the liver and kidney, transaminase in blood serum, variations in body weight and relation of weight liver/body weight. The method of analysis used to determine transaminase was that reported by Reintman and Frankel in 1957. The statistical method employed was the test of multiple comparisons based on the total ranges of Cruskal-Wallis. The results show that either significant differences were found (alpha = 0,05) among the groups (including the control), nor was necrosis observed or forming of tumors in the organs under investigation. Therefore, the doses administered does not seem to be toxic under the conditions of the experiment. Some signs of toxicity found in the group which was severely treated (10 mg of sodium nitrite and 20 mg of dimethylamine) appeared only in a few animals and it is necessary to verify the same in experiments with more animals and over a longer period of treatment.