Mongoose lemurs are the smallest species of the genus. They are 12 to 14 inches long with the tail 18 to 20 inches long. They weigh 4 to 4.5 pounds. They are woolly and the tails are bushy and gray in both sexes. Males have a gray body with red fur on the side of the body and the face. Males have white beards when they are born that turn red as they grow older. Females are darker gray than males and they have white fur on the sides of the body and face.