Long-term cell cultures (GI-LA-N and GI-ME-N) were established from the metastases of two disseminated neuroblastomas (NB). The first was obtained from a lymph node biopsy of a stage III NB after 7 months of chemotherapy, and the second from a bone marrow specimen of a stage IV NB after 6 months of chemotherapy. Cytogenetic investigation revealed several structural and numerical alterations in both cell cultures, but the only common chromosomal aberration was partial monosomy of 1p. Moreover, at the 5th in vitro passage, GI-LA-N displayed a high number of double minutes, not seen in GI-ME-N even after 33 subcultures. Molecular analysis revealed N-myc oncogene amplification in GI-LA-N cells, whereas, only one copy was found in GI-ME-N. No structural N-myc rearrangement was detected in either cell culture.