Super Kitty, a fourteen year old male castrated American DSH presented to the Cornell University Pathology Service for necropsy. He had had a year of vomiting, anorexia, and weight loss as well as a previously diagnosed hypertrophic cardiomyopathy and feline lower urinary tract disorder. Several diagnostic tests for feline infectious peritonitis were used in his evaluation with contradicting results. His necropsy results yielded a diagnosis of FIP grossly and histologically. This article uses this case to examine the diagnostic tests available and compare their diagnostic value in making a definitive diagnosis of feline infectious peritonitis.