Results of a prospective randomized clinical trial conducted by the WHO Collaborating Centers for the Evaluation of Methods of Diagnosis and Treatment of Melanoma are reported. Five‐hundred‐fifty‐three Stage I patients whose limbs were affected entered the study; 267 were submitted to wide excision and immediate node dissection and 286 had wide excision and node dissection at the time clinically positive nodes were detected. Survival curves of the two treatment groups could be superimposed. No subsets of patients benefitted from immediate node dissection. The authors conclude that delayed node dissection is as effective as the immediate dissection in Stage I melanoma of the extremities if the patient can be checked every three months. If the quarterly follow‐up is not guaranteed, immediate node dissection is advisable, at least for melanomas thicker than 2 mm. Copyright © 1982 American Cancer Society