Sickness absence data for periods of 1 week or more among 2385 London taxi drivers were analysed over a period of 1 year. The reasons, in order of decreasing prevalence, were accidents, disorders of bone and movement, circulatory disorders, and respiratory disorders. In order to place the absence rates of taxi drivers in perspective, a comparison over the same year was made with similar sickness absence data for the total work force (12 639) of bus drivers for London Transport. It was found that the bus drivers incurred about 3 times as many days of sickness absence (22.1 days per person compared with 65 days for taxi drivers) and 4 times as many spells of absence (0.73 spells per person compared with 0.16 spells for taxi drivers) as compared with taxi drivers. The main reason for these differences was considered to be due to the terms of employment including sick pay arrangements of the two groups.