The existing studies do not allow us to pinpoint LPR (and even less so GERD) as a clear-cut factor in the aetiopathogenesis of chronic sinusitis. However, despite all their deficiencies and limitations the studies nevertheless do show that reflux into the pharynx and nasopharynx is possible. This reflux (= LPR) can lead to chronic inflammation which can be successfully treated with antireflux therapy with proton pump inhibitors. Quantification of the association is not currently possible. An above-average proportion of the patients with chronic rhinosinusitis appear to have GERD/LPR. However the prevalence of GERD in the population is generally high. It has not yet been established with sufficient certainty whether the LPR must be regarded as a causative factor, whether it exacerbates or chronifies the disease or whether it is merely an epi-phenomenon which does not require specific treatment. To answer this important question we need prospective randomised controlled studies which will provide evidence of sufficient quality. These should be conducted with the help of standardised documentation.