In 1982 an outbreak of trichinosis occurred in an area of south Lebanon consisting of 4 villages, including 6440 persons. In 267 households, involving 2456 persons, typical clinical signs of Trichinella spiralis infection could be recognized among household members. Twenty-one of these households, including 193 persons, were randomly chosen for further studies. Nearly half of the household members (46%) had clinical symptoms consistent with acute trichinosis. 12 of 16 tested persons had high anti-Trichinella antibody titres (12 positive by indirect immunofluorescence (IIF) and 11 by enzyme-linked immunosorbent assay). Class-specific antibodies, IIF-immunoglobulin (Ig) G, IgM and IgA, were detected in most tested cases. Of the remaining 4 seronegative cases, 3 had a duration of clinical symptoms < or = 12 d. High peripheral eosinophilic counts (> 20%) were noted in 8 of 16 cases. In total, 15 of 16 cases were positive by one or more of these tests. The outbreak constituted one of the most extensive single outbreaks reported with a calculated > 1000 clinical cases. The cause was attributed to consumption of raw pork meat, an ingredient of kebbeh nayyeh, a favourite Lebanese dish.