Over a period of 32 years 689 patients with upper abdominal symptoms were examined radiologically at least twice for gall-bladder polyps and stones. All were without evidence of stones initially, but 181 had gall-bladder polyps on first examination. During a mean observation period of 9 1/2 years gall-bladder stones occurred in 18% (pigment stones in about 24%, solitary cholesterol stones in 30% and multiple ones in 46%), regardless of the presence or absence of gall-bladder polyps. There was no evidence for a change from polyps to stones. Cholesterolosis runs through four stages in the course of decades; accumulation of cholesterol esters in subepithelial foam-cell nests is characteristic. 95% of gall-bladder polyps are cholesterol polyps which gradually empty. Prophylactic cholecystectomy for gall-bladder polyps is justified only if they are more than 10 mm in diameter.