Pediatric tumors are the second main cause of childrens death in developed countries. Contrary to leukemias chromosomal alterations associated with malignant transformations are less well characterized for pediatric solid tumors. We present results of cytogenetic examinations of 262 pediatric solid tumors. Some of them were examined using by interphase fluorescent in situ hybridization (I-FISH), especially tumors where deletions or amplifications of specific genes and/or presence of fusion genes are known and could be used as diagnostic tool. Proven prognostic significance of the n-myc amplification, del 1p36, gain 17q, abnormalities on chromosome 11 are well known for children with neuroblastoma. For medulloblastomas i(17p), c-myc and i(12p) in germinal tumors are the other candidates. Vast majority of tumor samples were cultured and other possible chromosomal abnormalities were detected using FISH, spectral karyotyping (SKY) and comparative genomic hybridization (CGH). During last few months we have applied also high-resolution comparative genomic hybridization (HR-CGH). Cultivation of solid tumor tissue is not always successful, possible explanation could be generally low proliferation activity of tumor cells in vitro. Here we present our cytogenetic results together with clinical characteristics.