Introduction: Complementary (supplementary) and alternative (substitutive) treatment methods are autonomous healthcare practices that are being used by people throughout the world to preserve and promote health, and to prevent and treat diseases. All of these types of treatment work towards the health and satisfaction of citizens, but little is known about how much they are being used by patients with various chronic diseases. Purpose: The purpose of this bachelor’s thesis is to determine the use of complementary and alternative treatment methods among patients with internal diseases, namely: how many of them are using such methods, why they are using them and what their experiences were like, and whether their doctor has been informed of this. Work methods: A quantitative retrospective research study has been conducted, based on data obtained from the nursing documentation of intentionally selected adult patients with internal diseases, which was filled out by nursing students during clinical training in the 2013/14 and 2014/15 academic years. The results are presented in tables in descriptive form and numerically. Results: The research study encompassed 228 patients with internal diseases. 59% of them were women, 66% were over 60 years old, 52% were living in a town, 68% were living in central Slovenia, and 83% have finished secondary school or less. Most of the patients had cardiovascular diseases (46%), followed by metabolic diseases (13%), diseases of the blood and blood-forming organs (13%) and respiratory diseases (11%). The doctor asked 43% of the patients whether they were using complementary and alternative treatment methods. In the past 12 months, a quarter of them were using such methods, 31% of whom had seen a healer. Half of them decided to do so on their own and believe that the methods are effective, and that they go well with the conventional treatment; 44% of them have informed the doctor of this. Discussion and conclusion: We consider that the use of these methods, amond patients with internal diseases, is low. The patients have not received any information or advice on the safe use of complementary and alternative treatment methods. Healthcare professionals should take on the responsibility for informing them, but would need additional knowledge to do that. The use of such methods in nursing would ensure greater satisfaction, comfort and good communication between the patients and healthcare professionals.