The hepatic involvement of 57 patients with systemic lupus erythematosus (SLE) was studied with special reference to liver membrane autoantibody (LMA). Liver abnormalities were found predominantly in patients with active SLE (27/48 (56%) in active SLE v 3/20 (15%) in inactive SLE). They were, however, rather mild or moderate and tended to disappear as the disease activity of SLE decreased. In this respect the liver abnormalities observed in this study differed from those in patients with lupoid hepatitis. The incidence of LMA in active SLE (8/11 (73%] was significantly greater than that in inactive SLE (4/12 (33%)). The mean LMA index value in active SLE was 8.3, which was also greater than the 2.9 in inactive SLE. Furthermore, in active SLE the mean LMA titre was significantly higher in patients with liver abnormalities than in those without. These results suggest that LMA may be associated with the activity of SLE and may be one of the factors which cause transient liver abnormalities.