A characteristic sinusoidal tcPO2pattern was observed in 17(27%) of 62 patients with congenital heart disease manifested by cyanosis or heart failure during the neonatal period. All of these 17 patients were definitively diagnosed by cardiac catheterization, as having 8 PPA; 3 ToF; 2 TCA+VSD+PA; 2 asplenia with PA; 1 TGA+VSD+PS; and 1 TA (no TCA type). The transcutaneous oxygen pressure pattern of these patients showed a sinusoidal change with a cycle length of 6–20 min with the maximum pressure not exceeding 50 torr and the minimum pressure occasionally close to 0 torr. This sinusoidal tcPO2pattern was associated with various types of ductus‐dependent congenital heart diseases and hence may be of diagnostic value. Transcutaneous oxygen pressure monitoring is also useful in evaluating the ductal response to PG. Other possible mechanisms underlying this phenomenon including biological oscillation should be conside