A number of studies carried out in different countries have shown that farmers have a low morbidity and mortality in comparison to those in other occupations. However, this has been questioned on the basis that some type of selective process may be operating, in that persons having health problems will avoid farming, or are forced to leave farming for other occupations. To determine the occurrence of a so-called 'healthy worker effect', this postal survey of 'elimination' from farming and farming-associated occupations has been carried out. A total of 1283 male farmers and 334 male farm workers born in 1935 and active in Sweden in 1970 were taken as the study group. As controls, a similar number of occupationally active men of the same age and living in the same municipalities were randomly chosen. The results showed that farmers changed occupation or retired early less often than those in other occupations did, whereas more farm workers changed occupation and retired than did other workers of the same age. Among the different reasons given for work change/retirement, low income/poor earning capacity was more common among the farmers and farm workers than among the controls. Illness was less common among farmers but tended to be more common among farm workers as cause of work change. Few farmers changed their occupation because they were offered other work, in comparison to those in other occupations. Allergic disease more often led to an occupation change among farmers, while they less often gave cardiac disease and locomotor problems as a reason for change of occupation, this was probably also true for the farm workers.(ABSTRACT TRUNCATED AT 250 WORDS)