This report describes the fecalith-induced intestinal obstruction of a free-ranging red diamond rattlesnake (Crotalus ruber) and the snake's subsequent history following surgical removal of the fecalith. The captured snake exhibited an abnormally distended abdomen and an extremely hard mass, detected via palpation, near its vent. Coeliotomy yielded a 2.5-cm, 5-g fecalith from the large intestine. Microscopic dissection of the fecalith revealed no evidence of gastrointestinal parasitic worms. Subsequently, we implanted a radio-transmitter that allowed us to track the snake's movements for 7 months (until the radio signal vanished), indicating normal behaviour, complete recovery and good health apart from the obstruction. This observation suggests that fecalith development and intestinal obstruction represent potential risks of long-term faecal retention, an unusual physiological trait well documented among rattlesnakes and other stout, heavy-bodied terrestrial viperid snakes. Dehydration and decreased gut motility associated with brumation (≈hibernation) may predispose temperate snakes to fecalith formation. Regional drought and a small mammal diet with indigestible hairs might have also promoted fecalith formation in this specimen.