Prophylactic colchicine remains an efficacious drug in preventing recurrent attacks of acute gouty arthritis. Its use is indicated especially in those patients with frequent and severe attacks, and in those with coexisting medical complications. In the present study which reviews the experience of 540 patients, 518 males and 22 females over a period of more than 20 yr, excellent results were obtained in approximately 82% of the patients, the response was satisfactory in 12%, and unsatisfactory in 5%. Hyperuricemia per se did not offset the efficacy of the prophylactic regimen. Factors affecting the failure of the regimen were most frequently related to associated uncontrolled medical complications or intemperate habits of food or alcoholic beverages. Few patients were colchicine intolerant. No hematologic or renal toxic effects were observed with extended and regular ingestion of colchicine. At the dosage employed for prophylaxis 0.5 or 1.0 mg, colchicine was most likely involved in the suppression of chemotactic factors involving the synovial lining cells. There is no evidence of chromosomal aberration or infertility. Discontinuance of the prophylactic program may be attempted in any patient who has been free from recurrent attacks for several years, particularly in older patients with no medical complications.