The acute and subchronic toxicity (30 days) of N-aminomethylmorpholine-3,3-diethyl-2,4-pyridinedione (DKMM) and N-aminomethyl-piperazine-3,3-diethyl-2,4-pyridinedione (DKMP) was studied. The two compounds were found to have low acute toxicity. No changes are found in the haematological, urological and biochemical parameters, as well as in the histological tests of liver and parts of the cerebrum, after subchronic treatment with doses 150 there is an increase in GOT, GPT and the acid phosphatase. These results also correlate with the histological studies of the liver. The results of the acute toxicity show that DKMM and DKMP are weakly toxic substances (LD50 above 1500 mg/kg). Under conditions of the subchronic experiment the substances were tolerated very well by the animals, without causing lethality and essential toxicological changes in the organs studied.