Organizations have been even more knowledge-intensive and profession-orientated during the last years. Professional work has generally certain specific properties related to its working context. Professions working in organizations will add another dimensions of organization structure, culture, strategy and organizational effectiveness in creating, managing and sharing of knowledge. Two different case studies have been made, within two different work disciplines; within aircraft maintenance and emergency health care. This paper explores the conditions for knowledge management activities within different types of professions in the time- and life-critical work practices. The types of professions are called T- and L-professions. The aim of this paper is to examine the challenges of different types of professions characteristics on the knowledge creation, management and sharing in organizations dealing with time- and life-critical activities. Different characteristics exist of the T- and L-professions, respectively. The differences relate to different challenges within the knowledge management in organizations.