Nine persons in the county of Troms, Norway, were interviewed on their strict vegetarian diet. Improved health was indicated as the main reason for their choice of diet, but religion was a contributing reason for some. Most of the study persons would increase the intake of vitamin B12 if a deficiency state were to occur. One person reported, however, that she would not regard vitamin B12 deficiency as a health problem. The interviews disclosed beliefs regarding human physiology that are very far removed from standard scientific knowledge. The article indicates that communication between patient and the health care system may be difficult in such circumstances. Problems of communication would probably be minimized if the patient had a thorough understanding of human physiology and the health worker a thorough understanding of the reasons for the patient's choice of diet.