Plasma levels of the leucocyte adhesion molecule L‐selectin were measured by ELISA in 41 patients with rheumatoid arthritis, 18 with ankylosing spondylitis, 18 with systemic sclerosis and 27 with vasculitis together with 42 age‐ and sex‐matched controls. Low levels of soluble L‐selectin were found in systemic sclerosis (797 ± 302 ng/ml, P < 0.05) and vasculitis (941 ± 329 ng/ml, P < 0.05) relative to controls (1244 ± 269 ng/ml). The exact reasons for low levels of soluble L‐selectin are unclear, but may reflect reduced shedding from leucocytes and/or strong binding to its cell membrane ligand(s). An approximate inverse relationship between soluble L‐selectin and disease severity may have clinical relevance.