Infanticide, the intentional killing of conspecific infants, has been observed widely in mammals, including squirrels. Several ground squirrels revealed this behavioral anomaly, yet no report has been published on the flying squirrels. We report an observation of killing an infant of the particolored flying squirrel (Hylopetes alboniger) by a conspecific adult intruder in Satchari National Park of northeast Bangladesh. Among the several adaptive explanations for infanticide, our observations point to sexual selection in males that confers a competitive advantage by making females receptive. However, the resource competition hypothesis, where the intruder's offsprings gain access to resources as a result of the infanticide cannot be ruled out. Extensive studies are needed to document the extent of infanticide in flying squirrels and their adaptive significance.