Although disability is thought to be primarily a consequence of clinical disease episodes, there is some suggestion that it may also be present prior to clinically overt disease. There is little systematic information on the exact temporal relationship between clinical disease episodes and disability. Mendes de Leon et al examined changes in disability before and after acute myocardial infarction (MI) in a cohort study of 2812 adults 65 years and older, using yearly data on 3 disability outcomes for the 279 subjects who had an MI during follow-up. Compared with the period before MI, they found no evidence for greater disability increases after MI for 2 of the 3 disability outcomes. There was a greater increase after MI in disability in basic tasks requiring mobility and strength, but an exploratory analysis suggested that this increase started about 1 year prior to MI, rather than after the clinical event. Changes in disability after MI may form a continuation of changes that occur before the event. Increases in disability before MI may be related to progression of subclinical disease or age-related decline in other physiological processes.