The aim of the article was to study clinical manifestations of mumps infection (infectious parotitis) - a viral illness that affects glands that produce saliva, pancreas, and nervous system in children and adult patients. 219 patients (42 children and 177 adults) with mumps infection were studied. The investigation showed that parotid salivary gland disorder was the most common in adults; sublinguitis - inflammation of the sublingual gland was the most common in children. Serous meningitis occurred exclusively in preschool and early school age. Pancreatitis was less common in children than in adults. Infectious parotitis involving the parotid salivary gland was taking its normal course with positive outcome. Pancreatitis and serous meningitis occurred at the 3-5 day of illness with infectious parotitis. Pancreatitis was with positive outcome, with the exceptions of adult patients with pain syndrome (repair process delayed to 1-1.5 months). Mean duration of hospitalization for children with infectious parotitis was 7 days, for adults - 10-14 days. Mean duration of hospitalization for patients with serous meningitis was 14 days. Study showed that in 20,1% of 16-27 years old males developed orchitis.