5-Aza-2′-deoxycytidine (5-AZA-CdR) is an inhibitor of DNA methylation, and its antileukemic activity has been shown in preclinical and clinical studies. This paper describes the ability of 5-AZA-CdR to inhibit DNA methylation, DNA synthesis and cell growth in several human neuroblastoma cell lines. The stability of cell growth inhibition was ascertained, as well as the ability of the metabolite thymidine to enhance the antiproliferative effect of 5-AZA-CdR. The activity of phosphorylating enzyme deoxycylidine kinase (dCK) was correlated to different levels of sensitivity in several cell lines. The results obtained indicate that 5-AZA-CdR may be an agent for the chemotherapy of neuroblastoma.