Several vomiting episodes were reported in December 2007 by the management of a beach club in Calvià. The subsequent case investigation confirmed tuna fish consumption a few hours before onset of emesis in all cases. Microbiological analyses detected high bacterial levels in ready-to-eat fish samples, indicating inappropriate cooking procedures. More important, elevated levels of Bacillus cereus were present both in raw and cooked fish. No other pathogens were detected, indicating B. cereus as the etiological agent. To our knowledge, this is the first case of emetic disease by B. cereus likely to be associated with fish consumption.