Objectives: Prehypertension is associated with a higher risk of developing hypertension compared with normotension. Yet, factors predicting the development of hypertension among prehypertensive people are ill-understood. This prospective cohort study was performed to examine if serum gamma-glutamyltrasferase (GGT) within a normal range can predict the future risk of hypertension among prehypertensive adults. Methods: Study subjects were 293 prehypertensive persons >30-years-of-age who participated in a community-based health survey in 2003 and who were followed up in 2008. Sex-specific quartiles of baseline serum GGT were used to examine association with 5-year hypertension incidence. Results: Baseline serum GGT within normal range predicted the risk of developing hypertension for 5 years only in prehypertensive women. Adjusted relative risks were 1.0, 3.7, 3.6, and 6.0 according to quartiles of baseline serum GGT (P for trend <0.01). This pattern was similarly observed in non-drinkers. However, serum GGT was not associated with incident hypertension in men. Different from serum GGT, baseline serum alanine aminotransferase, another well-known liver enzyme, did not predict the risk of incident hypertension in both genders. Conclusions: Even though baseline serum GGT within normal range strongly predicted the future risk of hypertension, it was observed only in women, Although underlying mechanisms of this association are currently unclear, serum GGT can be used to select a high risk group of hypertension in prehypertensive women.