Eight cases of acute gastroenteritis caused by Vibrio parahaemolyticus in humans are described; to our knowledge, they are the first such reported cases in Spain. All cases appeared between August 20th and October 15th, with a frequency of 8.3% regarding the overall adult patients with acute gastroenteritis, and 11.5% regarding the overall patients with positive stool culture for any enteropathogenic organism. The eight strains were Kanagawa positive and in three patients other enteropathogenic organisms were isolated in addition to Vibrio parahaemolyticus, i.e. Aeromonas hydrophila in two and Salmonella serovariety enteritidis in another. In all cases fish or shellfish had been ingested outside the patients' homes; except for one patient, who ate living clams in the seaside of Galicia, all patients ingested them at seaside restaurants from the Barcelona province. The clinical features of acute gastroenteritis were definite in all patients, but no patients had significant electrolyte losses or required hospital admission. Recovery was spontaneous and no antimicrobial agents were required. All strains were sensitive to tetracyclines, aminoglycosides, cefotaxime, ceftazidime and nearly always to co-trimoxazole.