PIP: The incidence of subacute sclerosing panencephalitis (SSPE), a progressive and fatal neurodegenerative disease caused by the measles virus, has declined with widespread use of measles vaccine. The risk of SSPE after measles vaccination has been estimated at 0.7/million doses. This paper reports the case of a 15-year-old girl from India who developed SSPE presumably as a result of a delayed effect of measles, mumps, and rubella (MMR) vaccine. She presented with a 2-month history of behavioral disturbances, a deterioration in school performance, forgetfulness, silly smiling, handwriting changes, social withdrawal, and ataxia. The girl had received MMR vaccine at 9 months of age and had no past history of measles. Her measles antibody titre was 1:625 in both serum and cerebrospinal fluid.