Perfusion estimates and microvascular leakage (MVL) were recently correlated with glioma angiogenesis and aggressiveness, but their role in predicting outcome of patients (pts) with unfavorable low-grade gliomas (ULGG) is unclear. Their prognostic value was then investigated, versus conventional factors such as age, neurological status, tumor size, and contrast enhancement (CE). Clinical and anatomical magnetic resonance imaging (MRI) criteria of a cohort of ULGG pts were prospectively evaluated. A dynamic T2*-weighted MR sequence was included to detect high-perfusion areas, using the maximal value of the relative cerebral blood volume (rCBV) estimate, and MVL. Conventional and microvascular characteristics were correlated with progression-free survival (PFS). Among the 46 pts included, the following features were present in 61%, 26%, 67%, and 26%, respectively: age >or=40 years, neurological deficits, tumor size >or=6 cm, and CE. High perfusion value was noted in 30% of cases and MVL in 52%. With median follow-up of 22 months (range 4-46 months), median PFS was 32 months [95% confidence interval (CI) 17-45 months]. On univariate analysis, CE, rCBV, and MVL were significantly correlated with PFS. On multivariate analysis, only CE and MVL were unfavorable factors, with hazard ratio of 3.0 and 7.3 and P value of 0.04 and 0.02, respectively. Different prognostic subgroups were identified, with 2-year PFS of 86%, 57%, and 19% for pts with no MVL, MVL without CE, and MVL with CE, respectively. MVL and CE seem to predict short-term outcome in ULGG pts.