The aim of this study was to investigate the clinical characteristics of adult patients with BM metastases of solid tumors diagnosed by bone marrow (BM) aspiration. In this retrospective study, we reviewed the results of 3842 BM aspirations carried out in the Medical Oncology Unit in Hacettepe University between January 1993 and December 2004. Basic clinical characteristics of patients as well as sites of metastases and complete blood counts were obtained from the hospital records. Statistical analyses were performed using Statistical Package for Social Sciences (SPSS) for Windows version 10.0. Seventy-three patients (1.9%) had evidence of involvement of the BM by a solid tumor. Thirty-six patients were male (49.3%) and 37 were female (50.7%). Mean age was 49¡À13 (min: 17, max: 77). Breast cancer (28.8%) and lung cancer (23.3%) were the most common cancers associated with a BM metastasis. At the time of diagnosis, 68.5% of patients were found to have anemia, 58.9% thrombocytopenia, and 23.3% neutropenia. The most common site of metastasis associated with BM involvement was bone (n=51, 70.8%). Median survival after the diagnosis of BM metastasis was found to be 5 months and one-year survival was 28%. Patients with thrombocytopenia had significantly shorter median survival than patients with normal thrombocyte counts (1 month vs. 13 months, respectively; p <0.0001). BM involvement by solid tumors carries a poor prognosis, especially when thrombocytopenia is present. [Turk J Cancer 2007;37(3):85-88]