Sinusitis is one of the most frequent diseases in humans. Despite severe complications sinusitis may be considered a non-serious disease compared to other illnesses. Therefore, sinusitis is sometimes erroneously regarded as a banal disorder. It is mostly unknown that patients suffering from sinusitis may have a marked impairment of their quality of life (QOL). The term health-related QOL comprises physical and psychological well-being as well as aspects of daily life and social life from the patient's perspective. Validated measures (questionnaires) are able to quantify the impairment of QOL as well as the influence of therapy on QOL. Especially in the treatment of sinusitis, QOL becomes a relevant additional parameter due to the fact that clinical and subjective, patient-based criteria do not correlate sufficiently. This article provides an overview of available QOL questionnaires on sinusitis, highlights results of QOL studies in sinusitis, and elucidates the relevance of QOL in clinical trials as well as in the relation between the physician and the patient.