Acute stress promotes transient elevation of blood pressure, but there is no consistent evidence that this effect results in hypertension. In this systematic review of cohort and case-control studies that investigated the association between psychosocial stress and hypertension, we conducted a complete search up to February 2007 in MEDLINE, EMBASE, PSYCINFO and LILACS, through a search strategy that included eight terms to describe the exposure, six related to the design of the studies and one term for outcome. The quality was assessed by the Newcastle-Ottawa Quality Assessment Scale. The selection was done in duplicate by two teams of independent reviewers. Among 82 studies selected in the second phase, only 14 (10 cohort studies and 4 case-control studies), totalling 52,049 individuals, fulfilled the selection criteria. The average quality of the studies was 6.6+/-1.3 in a 9-point scale. Acute life events were associated with hypertension in one and were not associated in two studies. Five out of seven studies found a significant and positive association between measures of chronic stress and hypertension, with risk ratios ranging from 0.8 to 11.1. Three out of five studies reported high and significant risks of affective response to stress for hypertension, one a significant risk close to a unit and one reported absence of risk. Acute stress is probably not a risk factor for hypertension. Chronic stress and particularly the non-adaptive response to stress are more likely causes of sustained elevation of blood pressure. Studies with better quality are warranted.