During the period 1974-1983, Yersinia enterocolitica infection was diagnosed in 458 hospitalized patients by antibody response or isolation of the micro-organism. A total of 54 (11.9%) patients had acute liver infection, with significantly elevated serum levels (greater than or equal to 2-fold) of bilirubin and/or enzyme levels. Serious liver disease with cellular necrosis was observed in biopsy specimens from two of 12 patients examined; six had unspecific changes. The patients were followed up for 4-14 years (until 1987). A total of 22 (4.9%) patients were readmitted with chronic liver disease; in one case non-specific microscopic changes developed into granulomatous hepatitis over a period of 3 years. In both the acute and chronic stages of disease, liver involvement was associated with involvement of other organ systems, and some patients developed multi-organ disease. Chronic liver disease was associated with positive tests for antinuclear antibody and rheumatoid factor, and with a high mortality.