Synthesis of six prodrugs of allopurinol (4-hydroxypyrazolo-(3,4-d)pyrimidine) is described. These compounds were given orally to male and female BALB/C (sensitive) and C57BL/6 (partially resistant) strains of mice, wich had been previously infected with Leishmania mexicana. The results show that at end of the treatment there was weak regression of lesions confirmed through measurement of nodule diameter in the infected animals