Feline 'Injection Site Sarcoma' or 'Vaccine Associated Fibrosarcoma' is a rapidly progressive and aggressive cancer affecting cats. The true cause of the disease is not yet understood but it is definitely associated with the administration of long-acting injections like vaccinations. Vaccine technology has advanced since the condition was first reported in October 1991 and effective vaccinations now exist that have not yet been associated with this condition. Rapid appropriate action is required to give patients with this condition the best chance of a lengthy remission or cure.