Changes in the content and organization of doctoral studies have provided material for researching different aspects of doctoral studies. Much of the current literature concentrates on identifying the functions that an effective supervisor needs to carry out. Less attention has been paid to how well supervisors understand the aims of doctoral studies. The aim of this study was to describe the Estonian PhD supervisors' conceptions about doctoral studies. The study is based on semi-structured interviews with 21 PhD supervisors from educational science and exact and natural science disciplines. The data was analyzed using qualitative thematic data analysis techniques. The results show that according to supervisors' conceptions, the aim of a doctoral study is to prepare future researchers and acquire academic writing skills as quickly as possible. Doctoral studies are also seen as an intermediate process in the course of becoming a researcher.