A number of studies have reported that sleep duration might have an important role in the development of hypertension. However, the results have been inconsistent. In this study, a meta-analysis was performed to clarify the association between sleep duration and hypertension risk. PubMed, Embase and ISI web of science databases updated on 28 October 2011 were searched for eligible publications. Pooled odds ratio (OR) or relative risk (RR) with 95% confidence intervals (CI) was calculated using a random- or fixed-effect model. Six prospective (N=9959) and seventeen cross-sectional (N=105432) studies were identified for the data analysis on sleep duration. The results indicated that short sleep duration was associated with an increased risk of prevalent hypertension (OR=1.20, 95% CI: 1.09-1.32, P<0.001), especially among subjects younger than 65 years and females. In addition, short sleep duration was also associated with an increased risk of incident hypertension among subjects younger than 65 years (RR=1.33, 95% CI: 1.11-1.61, P=0.002). Overall, there was a significant association between long sleep duration and the risk of prevalent hypertension (OR=1.11, 95% CI: 1.05-1.17, P<0.001). Further subgroup analysis also suggested a significant association between long sleep duration and the risk of prevalent hypertension among subjects younger than 65 years (OR=1.12, 95% CI: 1.06-1.19, P<0.001). The present meta-analysis indicated that short sleep duration was associated with an increased risk of hypertension in the overall polulation and incident hypertension among subjects younger than 65 years. In addition, long sleep duration might be associated with a risk of prevalent hypertension, especially among subjects younger than 65 years.