Diltiazem is a widely used calcium channel blocker, and has been found to be effective in the treatment of hypertension, stable, variant and unstable angina, as well as oesophageal spasm. Calcium channel antagonists have been shown to diminish the contractility of gut smooth muscle, but have not as yet been reported to cause clinically significant inhibition of gut motility when used alone. We report a case of reversible functional intestinal obstruction, immediately following diltiazem treatment in a patient with ischaemic heart disease.