Commercial laxative use as a risk factor in colorectal cancer was investigated as one part of a large population based epidemiological study of colorectal cancer incidence, aetiology and survival "The Melbourne Colorectal Cancer Study", conducted in Melbourne, Australia. Commercial laxative use was similar in 685 colorectal cancer patients and 723 age/sex matched community based controls. Also, when laxatives were subdivided into various groups containing anthraquinones, phenolphthalein, mineral salts and others, previous laxative intake was similar between cases and controls. Previous use of anthraquinone laxatives and of phenolphthalein containing laxatives was not associated with the risk of colorectal cancer.