Groups of 2 to 4 sleep together during the day, then at night the adults forage singly or in pairs. They locate their slow-moving prey mainly by smell. The mother carry them for the first month and do not leave them alone until they are much more mature. They are born more helpless because the gestation period is a month less than it is for other Loris species. The shorter gestation is probably because of the mother's narrower body frame, which may not be capable of maintaining a pregnancy for as long as the more robust species.
Females emit a distinct series of high-pitched whistles to advertise their receptivity.
Several males may compete for a female in estrus, and will often mate with more than one male during a cycle. The eyes of the slender loris are said to be potent love charms, and are also used as cures for certain eye diseases. Therefore, many are captured and sold annually in India. They are also collected by snake-charmers, who use them as an object to amuse and attract crowds.