This study analyzed the effects of the chronic use of these drugs on the neuronal density of mice cerebral cortex and hippocampus. Materials and methods: 40 male Swiss mice were used, divided into 4 groups (n=10): GI-Control (0,02ml/Kg/week of saline solution), GII-treated with anabolic steroid Durateston® (83,3mg/Kg/week) GIII-treated with anabolic steroid Deca Durabolin® (16,6mg/Kg/week) e GIV-treated with the two anabolic steroids, concomitantly. The mice were treated for sixty days (60) and practiced swimming three times a week. The brain fragments were processed following the standardized sequence in conventional histological procedures and stained using cresyl violet. For the neuronal density analysis, the simple random count methodology was used. Results: Data revealed a significant reduction in the neuronal density of the groups treated with anabolic steroids, the limbic area had an estimated decrease of 16.44% in group III and 29.21% in group IV; the motor area the groups II, III, and IV presented a reduction of 17.63%, 15.35%, and 12.23%, and in the sensory area 15.22%, 16.41% and 21.59%, respectively; the groups II, III, and IV of the Ca1 area of the hippocampus showed a neuronal loss of 23.5%, 27.8%, and 36.36%, while groups II, III and IV of the Ca2 area there was a reduction of 10.37%, 11.83%, and 16.34%. In conclusion, the chronic use of AAS can be harmful to the nervous system since the neuronal reduction can bring structural and functional damages with possible consequences the whole organism.