We report ten cases with parotitis following the measles-mumpsrubella (MMR) vaccine which contains Edmonston-Zagreb measles strain, Leningrad-Zagreb mumps strain and Wistar RA 27/3 rubella strain (Tresivac (R), Serum Institute of India, India). The MMR mass immunization was performed in 1875 young adults in the recruit military center in January 2009. Nine of the vaccinated persons developed vaccine-associated parotitis as an adverse event approximately three weeks following immunization. One person, who had not been vaccinated recently, developed parotitis three weeks after contact with the vaccinated persons. The diagnosis of mumps was proven in eight patients by detection of serum IgM anti-mumps antibody and clinical fi ndings. Two patients with negative serology for mumps diagnosed by clinical and epidemiological fi ndings. Although it is well known that parotitis can occur as an adverse event after mumps vaccination, there are only a few reports of transmission of mumps via contact with vaccinated people. Following MMR vaccination, clinicians should consider parotitis as an adverse event and also the possibility of horizontal transmission of the vaccine strain.