The Authors carried out a research on the residues of Levamisole, a well known antihelmintic drug, in the muscles, livers, kidneys and blood from sheep treated with therapeutical doses. The results suggest that highest levamisole concentrations in the organs have been detected between the second and the third day (3.25 ppm in muscles; 1.40 ppm in livers; 0.22 ppm in kidneys). Remarkable residues have already been verified in blood during the first determination (4 h after the treatment) but these have been rapidly eliminated. Besides, a gradual diminution of the residues was observed until the seventh day from the treatment.