Epidemic parotitis, an acute infectious disease of respiratory tract, is marked by fever, swelling and pain of the subauricular parotidean region without definite borders. The disease results from the infection of mumps virus. It may occur during the four seasons of a year, but prevails in winter and spring. Clinically, school-agers and preschool children are more susceptible to the disease. Because of cross infection, the disease is liable to become epidemic in children in kindergartens and in low grades.Generally, the disease has favourable prognosis. The disease may also occur during adolescence and give rise to accompanying symptoms such as complications of orchitis in males and ovaritis in females. In a few severe cases,dizziness, headache, even unconsciousness, clonic convulsion, etc. may occur, giving rise to the complication of parotitic encephalitis. The patient can gain life-long immunity against parotitis after the recovery from the disease.