Patients (543) with bacteriologically confirmed pulmonary tuberculosis who successfully completed treatment were followed for 5 yr to determine relapse rates and to see whether any factors predispose to relapse. Practically the entire treatment of the patients was carried out in their homes. The cumulative relapse rate during a 5 yr period was 11.60%. Relapse rates were low during the 1st 2 yr of follow-up. Of the various factors considered in the analysis, age, sex, initial extent of disease or cavitation, and presence of initial or emergent drug-resistant bacilli did not influence the relapse rate. Patients who achieved complete radiographic clearing at the time treatment was stopped and those who were regular in treatment had comparatively low relapse rates. Cured patients were asked to report at least once annually for a checkup, and immediately if they developed any symptoms suggestive of relapse. Only 1/4 of the relapse cases were detected during routine annual checkup; in the remaining cases, the patients attended ahead of the next due visit because of symptoms. Doubt is cast on the utility of keeping cured patients under prolonged routine surveillance.