BACKGROUND Retrospective study of the Salmonella sp. strains and human salmonellosis episodes registered in the Public Health Laboratory of the Principado de Asturias, Spain, over the seven year period 1990-1996. MATERIAL AND METHODS All strains were serotyped; strains of serotypes Typhi and Typhimurium were also phage typed. The strains were grouped according to: sample of origin, age group; season of the year; time distribution, and epidemiological presentation (sporadic episode or outbreak). RESULTS AND DISCUSSION A total of 3,255 Salmonella isolates were registered and conserved in the period under study. They were adscribed to 45 serotypes, being Enteritidis, Typhimurium, Virchow and Hadar (57.1, 26.6, 4.5 and 2%, respectively) the most frequent. 3,193 isolates were collected from clinical samples (corresponding to 3,067 patients), 32 from environmental water or sewage, 28 from food and 2 from animal stools. Relevant epidemiological findings were: the most affected age group was children under 4 years old (32.3%), the season with highest incidence was the summer. The most frequent clinical presentation was the sporadic episode of gastroenteritis (97%). Seventy five outbreaks (22 communitary and 53 family) were registered, being associated with six serotypes: Enteritidis (76%), Typhimurium, Virchow, Hadar, Infantis and Coehl.