Forty-one free-living adult men with mild hypercholesterolemia (5.2-7.5 mmol/L) voluntarily participated in an 8-wk crossover study designed to determine the effect of prunes as a source of fiber on plasma cholesterol and on fecal output and bile acid concentration. During the prune period, subjects supplemented their usual diets with 12 prunes (100 g; 6 g dietary fiber) daily. Plasma low-density-lipoprotein cholesterol was significantly lower after the prune period (3.9 mmol/L) than after the grape-juice-control period (4.1 mmol/L). Fecal bile acid concentration of lithocholic acid was significantly lower after the prune period (0.95 mg bile acid/g dry wt stool) than after the grape-juice-control period (1.20 mg bile acid/g dry wt stool). Both fecal wet and dry weights were approximately 20% higher after the prune period than after the grape-juice-control period. Total bile acids (mg/72 h) did not significantly differ between experimental periods.