e19032 Background: Diffuse large B-cell lymphoma (DLBCL) is the most prevalent subtype of non-Hodgkin lymphoma (NHL). One third of DLBCLs cases have a primary extranodal origin and head and neck localization is second most common localization after gastrointestinal tract. The Revised-International Prognostic Index (r-IPI) is commonly used as prognostic tool, but there is growing evidence that neutrophil to lymphocyte ratio (NLR) also has prognostic significance in DLBCL. Methods: We retrospectively reviewed all cases of extranodal DLBCLs diagnosed between 2006 and 2016 at a single academic institution. Collected data included race, gender, primary site, baseline laboratory data, IPI score, pathology, treatment and survival. Results: A total of 33 patient were included, with 18 (54.5%) being females. Median age at diagnosis was 68 (range 28-92). 15% of patients had a r-IPI of 0, 30% a r-IPI of 1-2, 12% a rIPI of 3-5 and 36% a not evaluable (NE) r-IPI. Twelve (36%) patients had germinal center B cell subtype (GCB) and 17 (51%) patients had activated B cell subtype (ABC) by immunohistochemistry. Among all patients, 13 (39%) had pretreatment NLR equal or more than 3.5 and 11 (33%) patients had NLR less than 3.5 and 9 patients had a NE NLR. . Among deceased patients, 5 (56%) of them had NLR of more that 3.5 (p =0.011). Nine (27%) patients had pretreatment monocyte count less than 700/mm3 and 14 (42%) patients had monocyte count at least 700/mm3 (p=0.611). The 2-year overall survival was 77% (95% CI 0.61 - 0.93). Conclusions: (R-IPI) is the most common tool to predict outcome in DLBCL and our study showed that pretreatment NLR can be used as additional poor prognosis marker for patients with extranodal DLBCL of the head and neck. [Table: see text]