Oral habits are repetitive patterns of behavior involving the oral cavity, including digit sucking, lip sucking, tongue thrusting, nail-biting, object biting and bruxism, which has significant effects on health. Thumb sucking is the most common oral habit. Some of children who donotstop this habit, will give it up when their permanent teeth erupt, butthere is a tendency for continuing the sucking habit even until adult life. The present review describes thumb sucking, its etiology, clinical features and its management. Key words; Thumb sucking, digit sucking, proclination, management