Five captive white-headed langurs ( Trachypithecus leucocephalus) were observed day and night from March to May, 2008 in Shanghai Zoological Park using an instantaneous scan sampling method. Results showed that the langurs activity began at around 06:00 and ended at 18: 00 or 18:30 in spring. During the daytime, resting, feeding and moving were the main behaviors of the langurs. The mean frequencies were 13.79, 4. 75 and 2. 18, respectively. During the nighttime, the main behaviors were resting, moving and scratching. The mean frequencies were 22. 13, 0. 43 and 0. 26 ,respectively. Activity rhythm of moving, grooming, playing and other behaviors differed significantly among the individuals. No grooming and playing behaviors happened at night. The langurs had four small movement peaks at 21: 00, 00: 30, 03:O0 and 04: 30, and also had scratching peaks at 22: 30, 01 : 00,02: 00,03: 30,04: 30 and 05:30 from which we inferred that the langurs remained awake and alert during the long night. Moving behavior differed significantly between male and female langurs during the day and night.