To our knowledge, no reports on the impact of nicotine on the enzyme activity of the lysosomal system have been published yet. The study which is reported here is probably one of the first analyses of the models of lysosomal hydrolases of the liver and kidney of experimental mice which were exposed to various doses of nicotine. The aim of our experimental study was to analyze the impact of nicotine administered for 4 or 8 days in the dosage of 12 and 20 mg/kg body weight, respectively, on the activity of acid phosphatase and cathepsins D and L, i.e. lysosomal hydrolases of the liver and kidney of mice. The experimental group constituted 60 Swiss male mice, aged 8-9 weeks, of average body weight of 23.4 +/- 1.2 grams. We came to the following conclusions after the completion of the experimental study and laboratory analyses: - nicotine injected once a day in the dosage of 12 mg and 20 mg/kg body weight for 4 and 8 days caused a significant increase in the activity of acid phosphatase, and cathepsins D and L in the liver and kidney of the studied mice. The range of observed changes was related to the organ, the dosage and administration time; - the increase in the activity of studied enzymes after administering nicotine may indicate that the alkaloid exhibits destabilizing activity in lysosomal membranes of the liver and kidney cells, therefore it may affect metabolic pathways of those organs.