Necrotizing fasciitis is a rapidly progressive inflammatory infection of the fascia, with secondary necrosis of the subcutaneous tissue. The causative agents are usually aerobic and anaerobic bacteria. We report a case of necrotizing fasciitis with multidrug-resistant E. coli and complicated by mucormycosis, which is an invasive fungal infection. This rare infection occurred in a 40-year-old lady with carcinoma endometrium following elective surgery. Rapid clinical deterioration in the background of repeated negative bacteriological cultures should alert to a Mucor infection. As fungal etiology in necrotizing fasciitis is a rarity, any delay in initiating treatment can be fatal and a high degree of clinical suspicion is essential for prompt diagnosis. Management is by aggressive surgical debridement, negative pressure wound therapy and appropriate antifungals in addition to appropriate antimicrobials.