The objective of this study was to explore prognostic factors in lymphoma patients with bone marrow involvement (Ann Arbor stage IV). To that end, we analyzed a cohort study of 68 stage IV lymphoma patients. We found that the most predictive thresholds for lymphocyte rate, monocyte rate, and lymphocyte to monocyte ratio (LMR) were 30%, 13%, and 3, respectively. A lymphocyte rate <30%, a monocyte rate >13%, and the presence of B symptoms were associated with shorter OS. LMR > 3, Eastern Oncology Cooperative Group performance status <= 1, indolent lymphoma, and B cell (as opposed to T and NK cell) lymphoma predicted longer OS. Our study showed that these basic, easily acquired data can predict the outcome and overall survival in lymphoma patients with bone marrow involvement. These prognostic markers should be taken into consideration when devising new prognostic scoring systems for lymphomas.