The effect mechanism of pharmacological agents used in neuroblastoma treatment on myc-N expression is still unclear. Myc-N amplification does not change with any agent. The aim of this study is to investigate the effect of chemotherapeutic agents and retinoic acid on ultra structural localization of myc-N in neuroblastoma. We analyzed ultra structural localization changes of myc-N by immunoelectron microscopy in myc-N positive, Kelly human neuroblastoma cell line using retinoic acid and cytotoxic drugs (cisplatin, vincristine, cyclophosphamide, etoposide, doxorubicin) and their combinations incubated for 24 hours in preoptimised LD50 doses in cell culture compared with control conditions. Myc-N was applied by immunoelectron microscopy method using colloidal gold for visualisation. Results were scored semi quantitatively as negative, mild, moderate, or high positive in nucleus, ribosomal and cell membrane. Immunogold particles labeling myc-N was high in nucleus, ribosomes and low in cell membrane in control tumor cells without any drug. It was moderate in nucleus in retinoic acid, cyclophosphamide, etoposide, cisplatin and their combinations groups. The nuclear expression was mild in, vincristine, doxorubicin and their combinations groups. It was negative in ribosomes in all combination groups and doxorubicin and retinoic acid combined with vincristine group. Chemotherapeutic agents and their combinations caused a prominent decrease in myc-N expression in cell membrane, a medium level decrease in ribosomal level and a low decrease in nuclear ultra structural localization. Myc-N expression is reduced with cytotoxic agents and retinoic acid especially in ribosomal units. Retinoic acid combined with vincristine or doxorubicin is the most effective combination to reduce myc-N expression.