Numerous adult studies show a 30-65% response rate to azathioprine (AZA) or 6-mercaptopurine (6-MP) for significant perianal Crohn's disease. The aim of this study was to evaluate whether these drugs healed pediatric perianal Crohn's disease. Records of pediatric Crohn's patients were retrospectively reviewed for significant perianal disease treated with AZA or 6-MP for > or =6 months. The patient's perianal disease was reviewed and evaluated for fistulas, drainage, induration, and tenderness. In addition, the patients were given a score using the Irvine Perianal Disease Activity Index (PDAI). Patients were retrospectively scored upon initiation of treatment and after six months of therapy. Possible scores ranged from 0-20. Twenty patients met the study criteria. Five patients were considered treatment failures. One patient required a colostomy after 1.5 months of therapy, one developed pancreatitis, and three were noncompliant with therapy. Of the remaining 15 patients who were treated for > or =6 months, 67% had an improvement in drainage, 73% in tenderness, 60% in induration, and 40% in fistula closure. The mean Irvine PDAI was 7.67 +/- 2.19 initially and 4.40 +/- 1.72 after six months of therapy. The improvement was statistically significant (p < 0.001). AZA and 6-MP are effective treatments for healing significant perianal Crohn's disease in pediatrics.