Five outbreak clusters of Campylobacter jejuni occurred between March, 2002, and March, 2003, at the Washington State Penitentiary, in Walla Walla, Washington. Staff and inmates became ill. Over one-hundred persons tested positive with an identical strain of Campylobacter jejuni. The investigation identified a causal connection between a drain contaminated with pigeon feces on the roof and a leaking, uncapped, pipe in the kitchen salad preparation area. Other potential or specific causes of the contamination, including poor food-handling practices, were also documented as part of the investigation.