The calliphorid fly, Lucilia cuprina (Wiedemann), is known to cause serious malign myiasis in animals, whereas its sibling species Lucilia sericata (Meigen) is commonly a carrion breeder and is used in maggot debridement therapy (MDT). The current study reports an accidental involvement of L. cuprina in MDT in Alexandria, Egypt, that has proved to be safe and effective. In November 2008, the laboratory colonies of L. sericata (the species regularly used in MDT) at the Faculty of Science, Alexandria University were renewed by Lucilia flies collected as third instar larvae on exposed rabbit carcasses. Flies from the new colonies were successfully used to heal the diabetic foot wounds of two patients at Alexandria Main University Hospital. Analysis of DNA sequences and adult and larval morphology then revealed that these flies were and still are L. cuprina. Breeding of this species in carrion in Alexandria is a new record. Despite the safety of this strain of L. cuprina in MDT, entomologists rearing blow flies for the purpose of wound debridement should regularly maintain high quality assurance of their species' identity to avoid possible clinical complications that may result from the introduction of an unexpected and invasive species to their laboratory colonies.