INTRODUCTION: The purpose of this study was to review the literature concerning Necrotizing Fasciitis (N.F.) and to discuss a typical case where late diagnosis led to severe consequences. MATERIAL AND METHODS: A young male patient with no pertinent medical history, progressively developed a large swelling of his foot and severe pain 3-4 days following a simple contusion. The absence of an entry site lead to local incision without microbiological study. The patient developed blistering on the leg, then septic shock necessitating amputation. DISCUSSION: N.F. is an infectious necrosis of the sub-cutaneous tissue appearing frequently in surgical or post traumatic contexts. Streptococcal origin is classical but multibacterial anaerobic infection is more and more frequently observed. An entry site is not always found while the affected site becomes red, hot and painful. Evolution is extremely rapid with the appearance of blisters and cutaneous necrotic sites and a severe alteration in the general condition of the patient. The extent of sub-cutaneous necrosis is larger than the affected area of skin. N.F. is a surgical emergency. Treatment consists of complete debridement, sometimes very extensive and mutilating. High dose intra-venous antibiotic therapy is necessary while the benefits of hyperbaric therapy are discussed. Because of the lack of specific clinical signs, diagnosis is difficult and is often made too late. The rapidity of the evolution shows that vital and functional prognosis is better with early diagnosis and treatment even for patients without associated pathology. The rate of mortality is approximately 50 per cent. CONCLUSION: Better information of practitioners allowing a rapid clinical diagnosis could improve the prognosis which is still life-threatening in 1994.