Objective To determine the efficacy of radioisotopes to control metastasic pain in patients with tumor bone metastases and complications due to bone metastases (hypercalcaemia, bone fracture and spinal cord compression). The effectiveness of radioisotopes in relation to patient survival and adverse effects were also assessed. Methods MEDLINE (1966 to April 2005),EMBASE (1966 to April 2005), The Cochrane Library (Issue 1, 2005) and CBMdisc (1979 to April 2005) were searched for randomized controlled trials (RCTs). Data were extracted by two reviewers using a designed extraction form. The quality of included RCTs was critically assessed. RevMan 4.2 software was used for data analysis. Results Four RCTs were included. The results of meta-analysis showed that small dose of radioisotopes couldn’t control metastatic pain in short term(2 months) with relative risk (RR) 1.13, 95%confidence interval (CI) 0.34 to 3.76, but large dose can significantly control metastatic pain in medium term(6 month) with RR 1.90, 95％CI 1.23 to 2.92; no evidence was available to assess long term(≥12 months) effects. No study provided data on quality of life, mortality, bone metastatic complications (hypercalcaemia, bone fracture) and analgesic use etc. Leukocytopenia and thrombocytopenia were secondary effects associated with the administration of radioisotopes. The incidences of leukocytopenia and thrombocytopenia were significantly greater in patients treated by radioisotopes with RR 8.28, 95％CI 2.24 to 30.67, and RR 3.70, 95％CI 1.59 to 9.04, respectively. Conclusions There is some evidence indicating that large dose of radioisotopes can relieve metastatic bone pain over one to six months, but adverse effects, particularly leukocytopenia and thrombocytopenia, have also been experienced.