Several mechanisms, including altered local and systemic immune system, apoptosis, and new angiogenesis, are responsible for the development and progression of endometriosis. Over the years many markers have been studied, like CA 125 and, recently, neutrophil-to-lymphocyte ratio (NLR). This tool is cost-effectiveness and non-invasiveness as a marker of systemic inflammatory diseases. The aim of this study is to assess the role of NLR in the real-life management of patients with endometriosis in order to evaluate the possible association between this value and symptoms. We performed a retrospective analysis of 199 premenopausal women affected by endometriosis, from January 2013 to December 2020, evaluating the characteristics of disease, the symptoms and the NLR. Analyzing the neutrophiles, the mean ± SD value was 6.1 ± 4.5 × 103/ul, while for lymphocytes mean ± SD value was 1.8 ± 0.7.NLR was categorized according to its median value (> 2.62 vs ≤ 2.62). The comparison between NLR values and CA 125, endometriosis stage, dysmenorrhea and presence of chronic pelvic pain, adjusting for previous therapy did not find a significant association. An interesting result, although not significant, was the association between NLR and chronic pelvic pain (OR = 1.9). In the sub-group of patients without previous therapy this association is even stronger (OR = 4.8, 95% CI 0.5-50.2, p = 0.190). The link between NLR and chronic pelvic pain can provide a further hint to the clinician even when taking symptoms into account to develop a particular therapeutic treatment related to the various expressions of NLR. Finally, NLR may enable the creation of customized follow-up protocols that divide patients into high- and low-risk categories for endometriosis recurrence.