BACKGROUND: The frequency and severity of post-thrombotic sequelae after spontaneous axillary-subclavian venous thrombosis remain poorly known. OBJECTIVE: To determine the late sequelae of conventionally treated spontaneous axillary-subclavian venous thrombosis. DESIGN: Cross-sectional study. SETTING: University department of vascular medicine. PATIENTS: 54 patients seen during an 18-year period (mean follow-up, 5 years). MEASUREMENTS: Scores for the severity of post-thrombotic symptoms were graded on a numerical rating scale ranging from 0 to 10 and on a 6-point verbal rating scale. Ultrasonographic sequelae were classified as grade 0, normal flow; grade 1, moderate obstruction; or grade 2, severe obstruction or occlusion. RESULTS: Verbal scores were "nil/negligible" in 47% of patients and "severe/intolerable" in 13%; numerical scores were 0 to 3 in 78% of patients and 7 to 10 in 9%. Grade 2 ultrasonographic sequelae were found in 22% of cases. No relation was seen between ultrasonographic sequelae and symptom severity scores. CONCLUSION: The overall clinical outcome of spontaneous axillary-subclavian venous thrombosis is good, and there is no relation between the severity of late symptoms and ultrasonographic sequelae.