This paper presents a case study on the deep excavation in rock. The project site is located on the hill side of Neihu, Taipei city. The underlying sandstone and shale are covered by colluvium of varying thickness from lm to 10m. The excavation is 15m deep. There are three major concerns: (1)stability of the slopes on the north side, (2)stability of the slope and the safety of the adjacent buildings on the east side, and (3)general stability of excavation in rock. Extensive site investigations have been carried out. The excavation has been successfully completed under a very comprehensive monitoring program.