Abstract Background This study was designed to document the surgical anatomy of the saphenofemoral junction (SFJ). Methods The anatomy of the SFJ was recorded diagrammatically in 2089 consecutive groin dissections performed to treat primary varicose veins. The number of primary tributaries, bifid systems, junctional tributaries and the relationship of the external pudendal artery (EPA) to the long saphenous vein (LSV) were recorded. Results The LSV was bifid in 18·1 per cent of legs. The number of tributaries at the SFJ varied from one to ten. In 33·4 per cent one or more (junctional) tributaries joined the LSV or common femoral vein deep to the deep fascia. The EPA crossed anterior to 16·8 per cent of LSVs. In 4·6 per cent it passed posterior to one large tributary or trunk of a bifid LSV and anterior to the second trunk, making identification of the second trunk particularly difficult. Conclusion A thorough understanding of the anatomical variations of the SFJ is important in ensuring that the junction is managed safely and adequately in patients with varicose veins. Failure to appreciate these variations may account for a significant proportion of inadequate primary varicose vein surgery.