Nail changes of shape, discolouration and/or unusual markings should always be checked when faced with a patient in whom the diagnosis is uncertain; different appearances may give clues as to an underlying condition and a careful history, examination and sometimes further investigation may suggest an answer. Clubbing of the nails may affect both the fingers and toes. It presents as softening of the nail bed so that the nail appears less firmly attached, the angle between the nail and cuticle increases, the terminal part of the finger bulges and the nail curls over like an inverted spoon. For this 40-year-old man, with a congenital heart problem, clubbing had been present since birth, but sometimes clubbing will suddenly develop. Most commonly this will be associated with lung cancer but also problems such as bronchiectasis, cystic fibrosis or lung abscess, other malignancies, coeliac disease, liver cirrhosis, Grave's disease and hyperthyroidism may need to be considered. Clubbing may return to normal if the underlying condition is successfully treated.