The publication of different studies, articles and documents over recent years greatly justifies the revision of the year 2003 Consensus on the diagnosis and treatment of rhinosinusitis made jointly by the Spanish Society of Chemotherapy and the Spanish Society of Otolaryngology and Cervical Facial Pathology. The most significant features to be analyzed consider a new classification, the accumulated evidence on the role of first line of nasal corticosteroids, the demonstration of the utility of different antimicrobial agents with wide clinical experiences and the appearance of clinical studies with new antimicrobial agents that support their utility. Due to its evolution, rhinosinusitis is considered to be acute (viral or non-viral origin) if it lasts less than 12 weeks, chronic when it exceeds this time period and recurrent acute when three or more acute episodes are suffered in one year. Based on its severity, rhinosinusitis can be classified as mild, moderate or severe. Rhinosinusitis may present without or with complications. Rhinosinusitis symptoms resolve spontaneously in 40% of the patients. However, medical treatment is indicated to provide symptomatic relief, accelerate the resolution of the clinical picture, prevent possible complications and avoid evolution to chronicity. Antimicrobial agents and topical nasal corticosteroids (used alone or in combination with antimicrobial agents) are the treatments that have demonstrated therapeutical utility in rigorous and controlled clinical trials. In mild acute maxillary rhinosinusitis without previous antibiotic treatment, the treatment of choice is amoxicillin/clavulanate or cefditoren, while when it is moderate or mild in patients previously treated with antibiotics, levofloxacin or moxifloxacin are preferable, the amoxicillin/clavulanate or cefditoren drugs remaining as good alternatives. In the severe forms, third generation cephalosporins, such as cefotaxime or ceftriaxone, are indicated and amoxicillin/clavulanate or ertapenem are good options in the non-polypoidal chronic forms.