During burn care the wounds must be repeatedly debrided of adherent and loose debris until the decision is made to surgically excise and graft the wound or to await epithelialization. Though native proteolytic enzymes in the skin or those produced by colonizing bacteria can speed eschar separation, the use of exogenous enzymes for wound debridement may accelerate wound cleaning and healing. Collagenase digests native and denatured collagen in necrotic tissue. This multicenter trial of 79 patients with partial-thickness wounds compared the efficacy of collagenase ointment applied with polymyxin B sulfate/bacitracin powder with the efficacy of standard topical antimicrobial therapy (control) in which silver sulfadiazine cream (1%) was used to debride paired burn sites. Patients selected for the study had two noncontiguous, partial-thickness, comparably sized, and anatomically similar burn wounds. Ages of patients ranged from 5 to 60 years (mean 33 years). The total body surface area burned ranged from 2% to 30% (mean 13.6%). Mean burn sizes used for study treatment were 366 cm2 (26 to 2310 cm2) for collagenase sites and 355 cm2 (26 to 2394 cm2) for control sites. Sites on each patient were randomly assigned to treatment with either collagenase or control. Endpoints were time to clean wound bed (absence of retained debris) and time to healing (complete epithelialization). The sites treated with collagenase cleaned in less time (mean 9.3 days) than the control sites (mean 11.6 days). Similarly the collagenase sites healed faster than the control sites (mean 19 vs 22.1 days).(ABSTRACT TRUNCATED AT 250 WORDS)