Aerobic exercise and progressive resistance training have been shown to reduce resting systolic (SBP) and diastolic (DBP) blood pressure in adults. Recently, isometric handgrip (IHG) exercise has been commercially promoted as an approach for lowering resting SBP and DBP. PURPOSE: Use the meta-analytic approach to determine the efficacy of IHG exercise for reducing resting SBP and DBP in adults. METHODS: Studies were retrieved using five electronic databases (PubMed, Cochrane Central Register of Controlled Clinical Trials, CINAHL, Sport Discus and Dissertation Abstracts International) as well cross-referencing from retrieved articles. Studies were included if they met the following criteria: (1) randomized controlled trials with the unit of assignment at the participant level, (2) an IHG exercise intervention group, (3) IHG exercise > 4 weeks, (4) published and unpublished studies, (5) adults > 18 years of age, (6) studies published in any language between January 1, 1971 and February 1, 2009, and (7) data available for resting SBP and/or DBP. All data were abstracted using a dual coding procedure. Random-effects models using nonparametric 95% bootstrap percentile confidence intervals (BCIs, 5000 iterations) were used to pool results for resting SBP and DBP. The Q statistic was used to test for heterogeneity while the I2 statistic was used to test for inconsistency. Publication bias was examined using the approach of Duval and Tweedie (2000). RESULTS: Data for 81 men and women (42 exercise, 39 control) from three of 287 reviewed studies were pooled for analysis. Statistically significant exercise minus control group reductions of approximately 9% and 10% were observed for resting SBP and DBP (SBP, mean, -13.4 mmHg, 95% BCI, -15.3 to -11.0 mmHg; DBP, mean, -7.8 mmHg, 95% BCI, -16.5 to -3.0 mmHg). No statistically significant heterogeneity or inconsistency was observed (SBP, Q = 1.8, p = 0.42, I2 = 0%; DBP, Q = 2.2, p = 0.33, I2 = 18.6%). In addition, no publication bias was observed. With each study deleted from the model once, results remained statistically significant for both SBP and DBP. CONCLUSIONS: Isometric handgrip exercise is efficacious for reducing resting SBP and DBP in adult humans. However, a need exists for additional randomized controlled trials on this topic.