SUMMARY This report describes a 52-year-old black male with the isolated finding of an anomalous superior vena cava draining into the left atrium. The patient presented with dizziness, mild cyanosis, polycythemia and normal cardiac and pulmonary findings. The first major diagnostic clue in this confusing clinical presentation was an unsuccessful lung perfusion scan in which intravenous tracer consistently bypassed the lungs. This appears to be the first adult presenting with this rare anomaly. This condition should be suspected if cyanosis, clubbing, and a "normal" cardiac examination coexist and if the more common pulmonary and hematological causes of this triad have been excluded.