Cutaneous loxoscelism is an exceptional diagnosis in Portugal, regardless of the documented presence of Loxosceles rufescens.We report a 33-year old female patient presenting to our clinic after having visualized a bite from a spider in the inner aspect of the right thigh. Afterwards, she developed a warm, painful erythematous plaque, progressing to skin necrosis and torpid ulcer formation. Considering the failure of conservative measures, surgical debridement of the ulcer followed by repair using an O-Z plasty achieved good functional outcome. Definite diagnosis of cutaneous loxoscelism may be difficult since it relies on the visualization of the bite, capture of the spider for identification and typical clinical features. This case meets several criteria that allow the establishment of a causative link between spider bite and dermonecrosis. It is, to the best of our knowledge, the first diagnosis of loxoscelism reported in Portugal.