The L-myc, N-myc and c-myc genes are members of the myc oncogene family. In particular, L-myc is novel, and amplification of L-myc is still unknown except in small cell lung carcinoma. We examined L-myc amplification in 30 human neuroblastomas using Southern blot hybridization, and found that the L-myc gene was amplified approximately 5-fold in GOTO, a human neuroblastoma cell line. The N-myc gene was also amplified approximately 60-fold and furthermore, over-expression of L-myc and N-myc genes was observed in this cell line. In this report, we describe the coamplification of the myc gene family in the GOTO neuroblastoma cell line.