Gray Mouse Lemurs are among the smallest primates. Head and body length is 125-150 mm, tail length about the same, and weight ranges from 39-98 grams. They have soft fur, short snout, rounded skull prominent eyes and ears, long hind limbs and a long tail. Upper parts are usually grayish with a dark dorsal strip and distinct white median nasal stripe. Underparts are white.

They are arboreal, preferring secondary forests. They are nocturnal, traveling through the branches on all fours. They use their tails for balance when leaping. Nests are made in hollow trees or are spherical leaf forms in foliage.

Gray Mouse Lemurs are omnivorous, eating insects, spiders, flowers, nectar, fruit, some gums, small frogs and lizards, insect secretions, and leaves.

They are not true hibernators, but experience short periods of torpor during winter month. Breeding is confined to August through March with an estrous cycle of about 45-55 days. Gestation averages 60 days with average litters of 2-3 young. Young are weaned at about 25 days. Sexual maturity in females occurs at 10-29 months, males at 7-29 months.

Distribution is in W Madagascar, apparently from the far southwest to the Sambirano region.