Given the tendency of a proportion of sacrococcygeal teratomas (SCT) to recur, we evaluated whether serial tumor marker measurements are helpful in the management of these children. Between 1985 and 2006, 32 children with SCT were followed up for 1-15 years, and a total of 344, 197, and 193 serial samples for serum alpha-fetoprotein (AFP), CA 125, and CA 19-9 were analyzed, respectively. Six children with neonatal SCT developed eight recurrences. Serum AFP was elevated in two of two children prior to diagnosis of malignant recurrences (yolk sac tumor and adenocarcinoma), and CA 125 was elevated in one third of mature and one third of immature recurrences. CA 19-9 remained within reference values in relation to recurrences of neonatal SCT. Taken together, serum CA 125 measurements may complement the use of serum AFP in the follow-up of SCT.