We studied a bulk laxative containing methylcellulose in a group of normal subjects as well as in a group of chronically constipated individuals. The initial study in normal subjects was performed to show that the compound could increase fecal weight without significant side effects. Fifty healthy subjects were studied. Methylcellulose in daily doses of 4 g demonstrated a statistically significant increase in fecal frequency, fecal water, and fecal solids. In the second phase, we studied a group of 59 chronically constipated individuals treated with daily doses of the laxative containing either 1, 2, or 4 g of methylcellulose or 3.4 g psyllium. All of these doses resulted in statistically significant increases in stool frequency, water content, and fecal solids. There was no increase in individual stool weight from any of the laxative doses. Methylcellulose, in a daily dose as low as 1 g, is an effective laxative.