The deleted in colorectal carcinoma (DCC) gene, a candidate tumour suppressor, might be inactivated in a number of human cancers. In order to evaluate the possible role of DCC alterations in the pathogenesis of neuroblastoma, we examined 25 neuroblastoma cell lines and 16 primary tumours, including 6 samples with loss of heterozygosity (LOH) at the DCC locus for DCC mRNA expression, by using the reverse transcriptase-polymerase chain reaction (RT-PCR) technique. The level of DCC expression was significantly reduced or undetectable in 12 of 25 (48%) cell lines and 7 of 16 (44%) primary tumours, suggesting that inactivation of the DCC gene is involved in the development of neuroblastoma. Three of the 6 tumours with LOH at the DCC locus revealed reduced DCC mRNA expression, indicating that LOH at the DCC locus might have affected the levels of DCC mRNA. We also screened for mutations in 4 exons of the DCC gene in 12 cell lines by using PCR-single strand conformation polymorphism (PCR-SSCP) analysis. Point mutations were not found except a polymorphic change at codon 201. The mechanism for inactivation of the DCC gene will be further investigated.