Rhinosinusitis is a one of the most common upper respiratory tracts diseases, which affects from 6% to 15% of human population. Presence of pathogens, ostial obstruction and impaired drainage from sinuses have vital importance in illness development. Moreover, the risk of rhinosinusitis is increased with the associated risk factor such as: allergic rhinitis, anatomic defects of nasal septum and nasal cavity, primary ciliary dyskinesia, gastrooesophageal reflux, laryngopharyngeal reflux, congenital and acquired immunodeficiencies, cigarette smoke exposure. Because of the time of the clinical symptoms duration we divided the disease into acute and chronic. Symptoms of less than 12 weeks duration are considered acute and it is definitely more likely associated with viral infection. Persistence of signs and symptoms for more than 12 weeks is diagnosed as chronic rhinosinusitis and is often complicated by bacterial infection (mainly Streptococcus pneumoniae and Haemophilus influenzae). No single symptom or sign is an accurate predictor as they are varied and depends on age and inflammation localization. The diagnosis of rhinosinusitis is initially a clinical one. Radiologic confirmation is required only if the patient does not improve with empiric therapy or if she/he appears extremely ill, not as a primary diagnostic tool. The vast majority of patients should be effectively treated by decongestants, analgesics, antipyretics, mucolytics and oral rehydration. The use of antibiotics should be considered if there is no improvement only after 7–10 days of symptomatic treatment. In presented article we also describe two cases of children hospitalized in 2013 in Paediatric, Nephrology and Allergology Clinic, Military Institute of Medicine, which quite good illustrate diagnostic problems caused by symptoms diversification and the recurrence of the disease.