The habitual level of PAI-1 is influenced by many factors, of which obesity and insulin resistance are the most important. It is possible to reduce plasma PAI-1 by changes in life style, e.g. weight reduction and physical activity. Data on potential interactions between environmental and metabolic variables on one hand, and the 4G/5G-polymorphism on the other hand, are still scarce. It becomes more and more clear that PAI-1 may possibly not be a major (causal) factor in cardiovascular disease, but its role in inflammation deserves further attention. In the presence of the 4G-allele not only the PAI-1 response was more pronounced, but also the response of other acute-phase reactants, which implies that the increases of these reactants are secondary to the increase in PAI-1. A myocardial infarction also provokes an acute phase response. It can thus be hypothesized that the 4G-allele might exacerbate tissue injury during the acute phase after a myocardial infarction, and thereby negatively affect the prognosis.