Iodine labeled metaiodobenzylguanidine (MIBG) is a radiopharmaceutical employed for both diagnosis and metabolic radiotherapy of neuroblastoma (NB). Resistance to the radiotherapeutic effects of MIBG is common, due to lack of MIBG accumulation by NB cells. MIBG enters competent cells via the noradrenaline transporter; this function requires a relative cellular maturation and is missing in most NB cell lines. In vitro differentiation of NB cells can be achieved with gamma-interferon (gamma-IFN) and other agents. We have verified that gamma-IFN-induced differentiation of NB cells is specifically associated with an increase in their ability to incorporate MIBG. This phenomenon is due to enhancement of MIBG transporter activity, according to pharmacological sensitivity and semiquantitative PCR-based analysis of specific MIBG transporter mRNA. New therapeutic strategies based on both differentiation therapy and targeted radiotherapy of NB can so be devised.