Necrotizing fasciitis is a devastating soft tissue infection affecting fascias and subcutaneous soft tissues. Literature reviews have identified several related risk factors, including malignancy, alcoholism, malnutrition, diabetes, male gender and old age. There are only scanty case reports in the literature describing its rare association with colorectal malignancy. All published cases are attributed to bowel perforation resulting in necrotizing fasciitis over the perineal region. Isolated upper or lower limb diseases are rarely identified. Simultaneous upper and lower limb infection in colorectal cancer patients has never been described in the literature. We report an unusual case of multi-limb necrotizing fasciitis in a patient with underlying non-perforated rectal carcinoma. Necrotizing fasciitis is a devastating soft tissue infection affecting fascias and subcutaneous soft tissues. There are several related risk factors, including malignancy, alcoholism, malnutrition, diabetes, male gender and old age. There are only scanty case reports in the literature describing its Rare association with colorectal malignancy. All published cases are attributed to bowel perforation resulting in necrotizing fasciitis over the perineal region. Isolated upper or lower limb diseases are rarely identified. Simultaneous upper and lower limb infection in colorectal cancer patients has never been described in the literature We report an unusual case of multi-limb necrotizing fasciitis in a patient with underlying non-perforated rectal carcinoma.