Abstract Metabolic syndrome (MS) has recently been shown to be a forerunner of chronic kidney disease (CKD). Microalbuminuria (MA) is associated with both MS and CKD. This study aimed to prospectively investigate the relationship among MA, MS and renal outcome in non-diabetic patients with primary hypertension. A total of 790 hypertensive patients enrolled in the MAGIC study between 1993 and 1997 (mean age 49.3±10.7 years) were included in the analysis. Renal outcome was defined as the first hospitalization with a diagnosis of CKD. At baseline, 146 (19%) and 60 (7.6%) patients met MS and MA criteria, respectively. A total of 20 patients (2.5%) concomitantly showed MS and MA. After a median follow-up of 11.6 years (interquartile range 3.2 years), renal end point was reached in 15.8% of patients with MS and in 8.9% of those without it (P=0.0087). The incidence of renal events increased progressively starting from patients with neither MS nor MA, to patients with only one of these abnormalities and then to those with both. Significant interaction was observed between MS and MA. Patients with concomitant occurrence of MS and MA at baseline showed a greater than fivefold risk of renal outcome, as compared with patients with neither of these two risk factors (hazard ratio 5.46; 95% confidence interval 2.34-12.75). This risk became even higher when data were adjusted for potential confounders. MS and MA are independent and interactive predictors of renal outcome in non-diabetic patients with primary hypertension.