Evaluation of the impact of baseline absolute lymphocyte count, absolute monocyte count, and the lymphocyte/monocyte ratio, on the treatment response and prognosis in 100 patients with follicular lymphoma were presented. The study showed that absolute lymphocyte count, absolute monocyte count, and the lymphocyte/monocyte ratio at diagnosis are simple indices, which reflect the host systemic immunity and can predict the clinical outcomes in follicular lymphoma. Introduction: Recently, the lymphocyte to monocyte ratio (LMR) has been proposed as an easily determinable prognostic factor in patients with cancer, including lymphomas. The objective of this study was the evaluation of the impact of baseline absolute lymphocyte count (ALC), absolute monocyte count (AMC), and the LMR on the treatment response and prognosis in follicular lymphoma (FL). Patients and Methods: The data of 100 patients with a FL variant, admitted and treated between January 2009 and June 2018, were analyzed. Results: The area under the receiver operator characteristic curve and cutoff values of ALC, AMC, and LMR for discrimination between survival times using receiver operating characteristic curves showed 0.57 x 10(9)/L as the most discriminative ALC cutoff value, 1.235 x 10(9)/L as the most discriminative AMC cutoff value, and 1.63 as the most discriminative LMR cutoff value. Progressive disease and stable disease after first-line therapy and mortality rate were significantly associated with lower ALC, higher AMC, and higher LMR. Shorter overall survival (OS) was significantly associated with patients with lower ALC when compared with those having higher ALC. Shorter OS and progression-free survival (PFS) were significantly associated with higher AMC when compared with those having lower AMC. Shorter OS and PFS were significantly associated with lower LMR when compared with those having higher LMR. High-risk Follicular Lymphoma International Prognostic Index as well as low LMR were considered as risk factors for prediction of OS in all the studied patients with FL in univariate analysis and multivariate analysis. Conclusion: ALC, AMC, and LMR at diagnosis are simple indices, which reflect the host systemic immunity and can predict the clinical outcomes in FL.