The dissemination of prostate cancer cells to secondary sites appears to be an intermediate step in the formation of tumor metastases. However, the significance of tumor cell dissemination into the blood and bone marrow as well as the characteristics of these cells remains largely unknown. In attempts to correlate the presence of disseminated tumor cells with disease prognosis, studies have utilized a range of molecular and histologic techniques. The results of this research have been largely inconclusive in terms of clinical utility. Nevertheless, they have demonstrated that these cells are detectable and present much more often than would be expected based on the rate of prostate cancer recurrence. Further research has thus begun to focus on the isolation of individual disseminated tumor cells which can then be analyzed with techniques such as gene expression microarrays and comparative genomic hybridization in order to better characterize the cells. This review paper will examine the various methods of detecting disseminated tumor cells in patients with prostate cancer and the results of studies correlating these cells with clinical variables. Additionally, we discuss the isolation and analysis of disseminated cells and examine their potential value in helping to understand the relationship between these cells and tumor metastasis.