Epidermal phospholipase A2 (PLA2) in RA patients was significantly higher than in normals (p less than 0.0001) but lower than in psoriatic patients (p less than 0.05). No relationship was observed between PLA2 activity and commonly used measures of rheumatoid disease activity in a cross-sectional study. However, in a longitudinal study change in PLA2 activity correlated strongly with changes in disease activity.