This paper deals with a detailed field and laboratory study concerning Tuzla-Dragos Sewerage Tunnel in istanbul. First a brief description of the project is given and later the results of full-scale cutting tests, realized in the laboratory for performance prediction of a full-face tunnel-boring machine, are summarized. The equipment used for the tests is developed under NATO TU-Excavation Project in Istanbul Technical University, Mining Engineering Department. Rock samples were collected from tunneling side and different type of roller cutters and a conical bit were tested in the laboratory conditions and the performance of TBM was pre dieted using Specific Energy values obtained from cutting tests. In the second stage of the research program the in situ performance of the Robbins TBM is recorded and at the end the predicted performance values are compared with field values and some recommendations are made to tunnel contractors and practicing field engineer.