In knowledge intensive organizations mentoring has emerged as an efficient practice for the development of these personnel. In this scenario, software development has evolved in the previous years due to the impact of globalization. Global Software Development (GSD) emerged to cover specific aspects of distributed software development in global settings. Taking this into account, personnel development practices in GSD must be a focus of interest for both practitioners and academics alike. This paper presents an exploratory study conducted by means of a Delphi technique on the significance of mentoring practices in GSD teams. Results highlight the importance of mentoring for cultural, team working and behavioural issues and give less importance to technical issues related to software development.