Although head rotations are frequent patterns in play behavior in many mammalian species and differ from head movements used in other contexts, they have not been quantitatively described and their function remains unclear. The head rotations of free-ranging Hanuman langurs (Semnopithecus entellus) were described. Two hypotheses about their function were tested. Either the head rotations serve to create unexpected situations and should therefore occur in both solitary and social play and be very variable or they serve as play signals and should therefore occur only in social play and are ritualized. If head rotations have both functions, they should be less variable in social play. The results do not support the function of head rotations as play signals but, rather, suggest that head rotations may serve to create unexpected situations in play.