Immunohistochemical stains using neuronal and glial marker proteins were applied to retinoblastomas tissues from 14 children. Among the neurofilament triplet proteins, NF68Kd positive cells were observed in 12. Few NF160Kd positive cells were noted in 2, and NF210Kd positive cells were not detected. The positive ratio of NF68Kd and gamma-enolase seems to relate to the Flexner-Wintersteiner rosettes. Gamma-enolase positive cells were observed in 13. The distribution in tumor tissues was broader than that of NF68Kd positive cells. The immunoreactivities of NF68Kd were in parallel with those of gamma-enolase. Few GFAP positive cells were present around blood vessels, while S-100 protein and MBP positive cells were never observed. Our results indicate that retinoblastoma possesses predominantly neuronal properties, albeit in an immature form.