Objective. This prospective, randomized, open-label study controlled by active comparator aimed at assessing analgesic efficacy and overall tolerability of a burn treatment based on topic administration of unfractionated heparin. MethOds. Fifty eight male or female patients were randomly selected for conventional treatment (C group) or topical heparin treatment (TH group). Ages of patients enrolled ranged from 18 to 55 years. They had 2nd and 3rd degree burns on 10% to 30% of the body surface (BS) caused by fire or scald, no history of hemorrhagic diatheses, no hypersensitivity to heparin and less than 10% of the BS burned to 3rd degree. C group had frequent balneotherapy for injuries debridement and received silver sulfadiazine dressings. TH group had the first debridement and their burnt areas were left exposed to receive 4200 IU of unfractionated heparin topically for each 1% of burned BS, three times daily. Analgesic efficacy was evaluated in the 38 patients who completed the study according to the demand of analgesic medications and response to the pain Visual Analog Scale (VAS). Tolerability was evaluated from the files of all 58 randomized patients by the comparative incidence of adverse reactions. Results. The TH group demanded less analgesic medications (11.83 ± 9.38 per patient against 33.35 ± 20.63 for the group C, p<0.01), reported less pain in the VAS, had less fever and more bleeding than C group. There was no difference in the incidence of local infection, septicemia and safety exams. cOnclusiOn. The TH scheme presented higher analgesic effectiveness than C scheme without important tolerability problems.