Necrotising fasciitis (NF) due to group A β-haemolytic streptococci (GAS) is a rare but still life-threatening soft-tissue infection characterised by rapidly spreading inflammation and subsequent necrosis of the muscle fascia and of the surrounding tissues. Previous studies have emphasised that the outcome of patients with NF depends essentially on early diagnosis and treatment, consisting of extensive surgical debridement, along with appropriate antibiotic therapy. However, one of the striking features of the published series of GAS NF is that there was a delay in diagnosis in several cases, which underscores the difficulty of the early diagnosis of the condition. The goal of this article was to review the clinical features and diagnostic tools that could facilitate the early recognition of GAS NF.