The positive effect of Naftidrofuryl (Praxilene), a specific serotonine-S2 receptor antagonist, has already been described in the treatment of normal pressure glaucoma. Despite the fact that in POAG intraocular pressure (IOP) is the primary ethiopathogenic mechanism, vascular factors could also influence the progression of the disease, especially in old patients with cardiovascular risk factors. We have studied the effect of Naftidrofuryl versus placebo in a randomised double-blind study on 42 POAG patients. Visual acuity, IOP, Visual field (Octopus program G1), Arterial pressure, Plasma viscosity have been recorded at 0, 12 and 24 weeks. Our results showed no difference between the Naftidrofuryl and the Placebo group for each studied parameter except a decrease of CLV at 12 weeks in the Naftidrofuryl group (p = 0.012). This suggests that Naftidrofuryl is not as effective in POAG as it is in normal tension glaucoma. Other studies with a greater patient - collective and the use of other vasoactive substances will be necessary in the future.