We report the prevalence of metacarpal cortical thinning in systemic lupus erythematosus (SLE). Fifty-eight ambulant female patients attending a lupus clinic (mean age 32.4 years), were found to have significant thinning of metacarpal cortices (p < 0.05) when compared with 63 normal females (mean age 34.1 years). However, metacarpal bone mass was within the normal range. Measurements were made at 6 metacarpals of the 2 hands using a computer-aided technique (digitized radiogrammetry). Femoral cortical width and Singh index at the left femur, as well as the vertebral index at L3 were also recorded. The trabecular indices were in the range of normality, but the SLE group had more patients in the immediately pre-osteopenic range. Metacarpal bone loss was not related to disease duration or corticosteroid therapy. The prevalence of osteopenia in SLE is probably underestimated and the pathogenesis is likely to be multifactorial.