Persistent left superior vena cava (LSVC) with absent right superior vena cava (RSVC) is a very rare congenital anomaly. Its isolated existence is even rarer. Persistent LSVC is usually asymptomatic and discovered incidentally. We present persistent LSVC with absent RSVC in two asymptomatic patients, namely, a 52-year-old woman and 65-year-old man. The diagnosis was confirmed by cardiac computed tomography in both cases.