Respiratory illness occurred in members of a "package tour" to Benidorm, Spain, in 1973. Three of the tourists died with similar pneumonic illnesses, and 86 other travellers who had stayed at the same hotel also had respiratory illnesses. After the organism associated with the epidemic of Legionnaires' disease in Philadelphia 3 years later was identified, sera from patients involved with the "Benidorm episode" were tested. Evidence of infection with the Legionnaires' disease bacterium was obtained from sera from three of the patients who had died and from sera of two of the surviving tourists. Six of 16 members of the staff of the hotel involved had elevated titres to the LD bacterium, suggesting that there may be persistent or recurrent activity in a particular building or locality over a period of years. Surveys of travellers returning to Scotland have shown a large amount of illness, and studies are being conducted to determine the proportion caused by Legionnaires' disease.