Sinusitis is a very common disease frequently diagnosed and treated by both primary care physicians and specialists. Several problems, however, exist for the diagnosis and treatment of sinusitis. First, is the identification of patients solely on the basis of symptoms, because headache, rhinorrhea, and nasal congestion are extremely common in patients without sinusitis. The clinical dilemma is proper selection of patients for confirmation of the diagnosis. Another aspect is the quality of life of patients suffering from sinus disease, as sinusitis is clearly associated with considerable discomfort for the patient. Third, sinusitis can be underdiagnosed and can be the cause of other respiratory tract symptoms, for example, chronic cough, increased signs and symptoms of asthma, chronic bronchitis, chronic obstructive pulmonary disease, and cystic fibrosis. In addition, patients with decreased immunity, for example, cancer and patients with HIV have a higher incidence of sinusitis. This article reviews the latest knowledge in the pathophysiology of sinusitis and its treatment.