The demand tor bored piles with high load capacity, especially as foundation for high rise build-ings and bridge foruidations is increasing. Pile construction with the rotary Kelly system is the most versatilesystem for installing piles to depth of 80 m and more, for pile diameiers of 3,5 m and for working in rock withstrength of 200 MPa. Methods, equipment and tools for the construction ot' rotary bored piles are explained inthe paper. The versatility ot- the kellv system is demonstrated on several case histories trom all over the world.