PURPOSE:Nifedipine (administered orally or applied topically) has been effective for nonsurgical treatment of anal fissure. We compared the efficacy of nifedipinevs.glyceryl trinitrate for chemical sphincterotomy of anal fissure.METHODS:In a prospective, double‐blind trial, 52 patients suffering from chronic anal fissure were randomly and equally allocated to receive either glyceryl trinitrate or nifedipine, both applied topically to the perianal region. The end point of the study was healing within a predetermined period (6 months). Variables assessed included demographic data (age, gender), symptoms associated with the fissure, duration of treatment, percentage of healing, untoward effects of treatment, pain scores, duration of follow‐up, recurrence, and need for complementary means of treatment. Descriptive data are presented as mean ± standard deviation and quantal data as percentage. Inference analysis was performed using the Student'st‐test for the descriptive data and the chi‐squared or Fisher's exact test for nominal variables.RESULTS:No significant differences were recorded with regard to age, gender, symptoms associated with the fissure, or duration of treatment. Healing rate was higher (P< 0.04) with nifedipine (89 percent) as compared with glyceryl trinitrate (58 percent). Treatment side effects (headache, flushing) were more frequent (P< 0.01) with glyceryl trinitrate (40 percent) as compared with nifedipine (5 percent). Pain scores were significantly lower (P< 0.03) on completion of treatment in both groups (3.2 in glyceryl trinitrate and 3.4 in nifedipinevs.6.2 and 6.1, respectively), but did not differ between the two groups. Recurrence occurred in 31 percent of patients treated with glyceryl trinitrate and 42 percent of those treated with nifedipine after a mean period of 18 ± 3 weeks and 12 ± 4 weeks, respectively.CONCLUSION:Topical application of nifedipine for management of chronic anal fissure was more effective and had fewer side effects than topical glyceryl trinitrate. Recurrence was frequent with both drugs.