Objective: Despite the advanced therapy with statins, antithrombotics, and antihypertensive agents, the medical treatment of atherosclerotic disease is less than optimal. Therefore, additional therapeutic antiatherosclerotic options are desirable. This pilot study was performed to assess the potential antiatherogenic effect of the peroxisome proliferator-activated receptor-γ agonist pioglitazone in nondiabetic patients. Methods: A total of 54 nondiabetic patients were observed in a prospective, double-blind, placebo-controlled study. Patients were randomized to pioglitazone or placebo. The following efficacy parameters were determined by serial analyses: artery pulse wave analysis and carotid-femoral pulse wave velocity (PWV), static and dynamic retinal vessel function, and the common carotid intima-media thickness (IMT). The main secondary endpoint was the change in different biochemical markers. Results: After 9 months, no relevant differences could be determined in the two treatment groups in PWV (pioglitazone 14.3 ± 4.4 m/s vs. placebo 14.2 ± 4.2 m/s), retinal arterial diameter (pioglitazone 112.1 ± 23.3 μm vs. placebo 117.9 ± 21.5 μm) or IMT (pioglitazone 0.85 ± 0.30 mm vs. placebo 0.79 ± 0.15 mm). Additionally, there were no differences in the change in biochemical markers like cholesteryl ester transfer protein, low-density lipoprotein cholesterol, high-sensitivity C-reactive protein or white blood cell count. Conclusions: Treatment with a peroxisome proliferator-activated receptor-γ agonist in nondiabetic patients did not improve the function of large and small peripheral vessels (PPP Trial, clinicaltrialsregister.eu: 2006-000186-11).