Medical nurses / technicians are not bound to patient care only, but they supervise and manage the quality and quantity of medical care, collect, evaluate, analyze, interpret and present data, along with planning the wholesome medical care for patients. Their tasks are the investigation of public health problems, estimation of risk factors, planning and conducting systematic, evaluated and controlled medical care, development of critical analysis, using informatics technologies, as well as planning, participating in, and conducting research projects. Through their activities as the members of interdisciplinary and medical teams, medical nurses / technicians are promoting health care system. Along with comprehensive education, medical nurses / technicians must not neglect the fact that they are the first link for a patient with the health care system and his/her illness, but also with his/her family facing the patient’s illness and life style. As the team members, medical nurses / technicians develop and promote the improvement and maintenance of the population’s health, advancement of life habits, with the aim of advancing the health of the whole nation. Giving help to people who suffer from illnesses, but also helping them to connect with health care institutions, is the primary duty of medical nurses / technicians. Highly educated medical nurses / technicians are qualified for numerous interventions within medical care for mentally ill persons in biological, psycho- and socio-therapeutic approach. In this work will be described competencies and interventions in biological treatment of mentally deranged persons.