BACKGROUND The medical profession's focus on dealing with negative mental states has led to the suggestion of classifying 'happiness' as a major affective disorder (pleasant type). OBJECTIVE To describe the symptoms and signs of happiness and discuss its health benefits. CONCLUSIONS Epidemiological data suggests that happiness is related to personality factors such as high self esteem, feelings of personal control and extroversion and is unrelated to demographic factors or the ownership of consumer goods. Humour is a communication device specifically designed to elicit joy and happiness and is effective in relieving anxiety and stress and enhances communication in medical settings. Recapturing the optimistic enchantment with life that is a part of childhood may be a key to happiness and health.