Abstract Purpose Necrotizing fasciitis (NF) is a severe soft tissue infection with a high morbidity and mortality. With early diagnosis and treatment this could be reduced. Unfortunately, the diagnosis of necrotizing fasciitis can be very difficult. In recent years many risk factors have been identified. In 2004, the Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score was developed. A tool that could help diagnosing NF. In this study, we search for prognostic factors for mortality in necrotizing fasciitis. Methods All adult patients with histopathological or surgical confirmed NF needed to be admitted to the intensive care unit for at least 24 h between January 2003 and December 2017 in five hospitals from the Nijmegen teaching region were included. We excluded patients with other forms of soft tissue infections or patients with an intensive care unit (ICU) stay of < 24 h because we exclusively wanted to include patients with a fulminant course of necrotizing fasciitis. Results We have included 123 cases. The overall mortality was 31.7% ( N = 39). The overall mean LRINEC score was 7.4 ± 2.7. Patients who died as the result of NF had a significantly higher median LRINEC score (8 vs. 7, p = 0.034). Other parameters found to be associated with mortality are age ≥ 60 years, cardiovascular disease in the medical history, ≥ 2 comorbidities, and lactate level greater than 1.7 mmol/L. Conclusion LRINEC score should be calculated in all patients presenting with NF to provide an additional source for clinical outcome. A high LRINEC score could implicate a higher risk of mortality. Especially in elderly patients, with a cardiac history, more than two comorbidities or a lactate level greater than 1.7 mmol/L.