This study investigates if food sensitivity and which food ingredients might be responsible for this food sensitivity in 55 cats with chronic idiopathic gastrointestinal problems. Food sensitivity was confirmed in 16 cats by elimination and challenge trials with commercial diets with selected protein sources, and 8 cats were sensitive to more than 1 ingredient. The most common clinical signs in food-sensitive cats were coexisting gastrointestinal and dermatological signs, weight loss, and large-bowel diarrhoea. Neither antigen-specific IgE nor gastroscopic food sensitivity tests were helpful.