A gene called fbl, encoding a Staphylococcus lugdunensis fibrinogen-binding protein, was identified by phage display. The encoded protein, Fbl, is a member of the Sdr-family, a group of staphylococcal cell surface proteins containing a characteristic serine-aspartate repeat region. The fibrinogen-binding domain was mapped to 313 amino acids, and shows 62% identity to the corresponding region in clumping factor (ClfA) from Staphylococcus aureus. Anti-serum against ClfA cross-reacted with Fbl, and blocked S. lugdunensis adherence to fibrinogen. Twelve clinical isolates of S. lugdunensis analysed by Southern blot all had an fbl-like gene.