Osteosarcoma (OS) is the most common primary malignant tumor of bone; it occurs most commonly in the metaphyseal regions of long bones in adolescents and young adults. Conventional osteosarcoma is characterized by complex karyotypes with a high degree of aneuploidy and numerous structural aberrations such as copy number alterations (CNAs) and genomic rearrangements. The data comprise of array copy number data (N=113) from pre-therapeutic osteosarcoma. These have been derived from Affymetrix CytoscanHD. The study searches for driver genes and examines cancer evolution. Note (added 8th June 2016): This experiment is extended in an experiment described under accession E-MTAB-4815. It contains data for 97 samples from this experiment are also included in E-MTAB-4815.