Four subspecies of Otolemur garnettii are recognized: This species has a large body size relative to other galagos.

[4] The coloration depends upon subspecies: O. g. garnetti exhibits green-tinged reddish brown dorsal pelage.

O. g. kikuyuensis exhibits iron gray fur tinged with green on its back, flanks and limbs.

O. g. panganiensis is reddish brown to gray lacking the greenish hints in other species, while the ventral surface varies from white to yellow.

[3] This species exhibits significant degree of sexual size dimorphism with males larger than the females.

This is due to bimaturism, where males have a longer period of growth and have an average 19% greater body mass than females.

[3] The actual geographic range of each subspecies is as follows: O. g. garnetti is restricted to Zanzibar and the Pemba Islands.

O. g. lasiotis is found along the Kenyan coast as far north as the Juba River and south to Tanga Region, Tanzania.

They tend to focus on a particular portion of their home range for several nights while foraging, then move on to concentrate on a new section after a short time.

[4] Greater northern galagos are solitary and live and forage in their home range marked by urine and scent gland on chest.

[7] The northern greater galago penis is on average 18 mm in length and width of shaft is even from body to bottom of tip.

[3][6] Mothers carry their infants with their mouths to nests and leave them while they forage, returning to nurse their young.