To assess the conclusiveness of the Cochrane reviews (CRs) in the field of palliative and supportive care for cancer. We searched the CRs on Pain, Palliative, and Supportive Care Group available in the Cochrane library on February 01, 2015, to analyze whether a CR could reach a clinical decision. Each CR was analyzed for conclusiveness, number of randomized controlled trials (RCTs) enrolled, number of participants enrolled, the need for further studies, and the reasons. Only 45% (30 of 66) of the CRs reached definitive clinical recommendations. The number of RCTs and participants enrolled in conclusive CRs were significantly higher than those in inconclusive CRs. Nearly all CRs recognized the need for further studies. The conclusiveness was not affected by the year of publication. We concluded that a large number of clinical trials were not carried out well in the palliative and supportive oncology.