Cytokine receptor expression in human osteosarcoma cell lines (U2-OS, Saos-2, MG-63) was analyzed by flow cytometry to identify receptors which may interact with osteosarcoma cell growth and that should not be used in a clinical setting. U2-OS, Saos-2, MG-63 and bone marrow stromal cells, that were used as normal controls, constitutively express the FAS and SCFR surface molecules. GM-CSFR is expressed only by U2-OS and Saos-2 cell lines, that are phenotypically less differentiated than MG-63. Different gp130 clones were express ed only by Saos-2 and MG-63 cell lines. IL-2Rgamma,IL-7R and 4-1BB were expressed only by Saos-2 cell line. These data add new evidence of receptors that may be activated by autocrine or paracrine cytokines that could induce osteosarcoma cell growth.