This study reports the findings of one of the stages of a programme for the detection and control of arterial hypertension, started in 1980 in an automobile company with a workforce of 9,782. In the initial screening, 522 hypertensive males were found using epidemiological criteria and 206 of these fulfilled the criteria of definite hypertension. The objective of this study consisted of evaluating, 9 years after the start of the program, the indirect cost in terms of the reduction in the morbidity indicator-temporary work incapacity (TWI). Analysis is based on a comparison of the prevalence of hypertension in the population when the program was begun (6%) and in 1989 (9.8%). It can be observed that the TWI rate of the hypertensive population was significantly higher than that of the rest of the workforce, and that this remained true for the reference group (RG) hypertensives a year after the study was initiated. In contrast, the intervention group (IG) showed significantly lower TWI levels, not only in comparison with the RG but also with the rest of the workers. The estimated reduction in TWI for 1989 was 4.500 days/year, which corresponds to an estimated saving of 76.500.000 pesetas/year.