Measurement of serum concentrations of tissue polypeptide-specific Antigen (TPS) has been demonstrated to the useful in diagnosis and monitoring of adult epithelial tumors. So far, no data have been available on normal or pathologic TPS values in children. Therefore, the present study was designed to evaluate the normal values of TPS in childhood. Using a commercial enzyme linked immunosorbent assay (ELISA) kit, serum TPS was determined in 361 healthy children. Median (M) TPS was found to be 107 U/l at birth (n = 124). By the end of the first week, the value rose to M = 150 U/l (n = 68) and then continuously decreased with age (1 week-1 year, n = 45, M = 88 U/l; 1-7 years, n = 75, M = 51 U/l) until reaching the adult level (8-18 years, n = 49, M = 34 U/l). Additionally, the serum TPS values of 45 mothers right after delivery (M = 161 U/l) were assessed, and there was no correlation to the marker levels determined in the cord blood of their children. The age-dependent distribution of serum TPS in healthy children must be taken into account in the clinical application of this tumor marker.