Nivolumab response rate is 40% in metastatic melanoma. Few studies have evaluated pre-treatment biomarkers predictive of response. The aim of this study was to identify potential peripheral blood biomarkers associated with survival in patients with advanced melanoma treated with nivolumab. All advanced melanoma cases treated with anti-programmed cell death protein 1 (anti-PD1) over a 3-year period in the Dermato-Oncology Department, Nantes, France were identified. For each case, 9 potential blood biomarkers were identified. Bivariate and multivariate analyses, adjusted for the American Joint Committee on Cancer (AJCC) classification stage, Eastern Cooperative Oncology Group (ECOG) performance status, lactate dehydrogenase (LDH) level and failure to respond to first-line therapy, were used to test the association between biomarkers and overall survival (primary outcome) or progression-free survival (secondary outcome). Increased monocyte count, leukocyte/lymphocyte ratio and neutrophil/lymphocyte ratio were significantly associated with decreased overall survival after bivariate and multivariate analyses. Increased monocyte count was also significantly associated with decreased progression-free survival. These blood variables are easily measured and could help to predict patient response before the introduction of anti-PD1 therapy.