Objective: to assess the usefulness of a risk scale based on serum procalcitoninwhen compared with the LRINEC score in the early discrimination between necrotizing fasciitis (NF) and extremities cellulite.Material and method: retrospective study, between 2009 and 2017, of all patients with the confirmed diagnosis of NF in one limb (N = 10). The findings of these patients were compared with those of 23 patients who were admitted for severe cellulitis of limbs in the same period. The variables related to each group were analyzed. Using the area under the curve (AUC), the discriminationcapacity for NF diagnosis of two scales was compared, one based on procalcitonin levels and another based on the LRINEC score.Results: the area under the curve was greater for the risk categorized by procalcitonin levels. When analyzing the LRINEC score and procalcitonin levels as continuous variables, the latter also presented a larger area under the curve. The cut-off point with the greatest area under the curve was that corresponding to> 0.87 ng / ml of procalcitonin (sensitivity of 100% and specificity of 82.6%) and score 5 on the LRINEC score (sensitivity of 80% and specificity of 82.6%).Conclusion: in our sample the level of procalcitoninand the scale based on this level has been shown as a more sensitive and at least as specific tool as the LRINEC scale for early discrimination between NF and a cellulite of the extremities.