PURPOSE: Biomarkers are needed to guide treatment decisions in recurrent ovarian cancer, as a high proportion of patients do not benefit from treatments. Data on immune subsets in patients receiving chemotherapy are scarce. We investigated the impact of T cells, B cells, neutrophils and the neutrophil-lymphocyte ratio (NLR) in ovarian cancer patients receiving palliative chemotherapy. METHODS: Blood samples were collected prospectively at baseline in recurrent ovarian cancer (N = 72) receiving chemotherapy. T cells, B cells, neutrophils, and NLR were analyzed. Primary and secondary endpoints were overall survival (OS) and treatment response, respectively. Cut-offs for T and B cells were predefined. RESULTS: In patients with low vs. high T and B cells counts, OS was 6.1 months vs 12.0 months (P = 0.017) and 6.1 months vs 12.0 months (P = 0.011, respectively. Low T and B cells analyzed as continuous variables were also associated with unfavorable OS, P = 0.011 and P = 0.007, respectively. Neutrophils had no significant prognostic impact. Median NLR was 4.1. High vs. low NLR was associated with poor survival, 7.4 months vs. 15.9 months (P = 0.012). In multivariate analysis including platinum sensitivity, number of prior lines of chemotherapy, and performance status, high NLR remained an independent poor prognostic factor HR: 2.17 (95% CI 1.21-3.88) (P = 0.009). High NLR was also significantly associated with lack of response, OR 0.15 (95% CI: 0.04-0.51) (P = 0.002). CONCLUSION: In recurrent ovarian cancer patients undergoing palliative chemotherapy, low T and B lymphocyte counts had an unfavorable prognostic impact. High NLR was associated with lack of response and a poor prognosis, and the parameter may be used in patient counselling and treatment decisions.