Background Doctors are in a good position to provide nutrition advice to patients. However, doctors and medical students find their nutrition education to be inadequate. We evaluated nutrition-related knowledge, attitudes and self-efficacy in a sample of future doctors. Furthermore, we investigated the association between nutrition-related knowledge, attitude and self-efficacy. We also compared nutrition-related knowledge, attitudes and self-efficacy with level of clinical training. Methods Following a cross-sectional design, the nutrition-related knowledge, attitudes and self-efficacy of 207 undergraduate clinical-level medical students (referred to as future doctors) was measured using a questionnaire. Items of the questionnaire were derived from previously validated survey instruments. Descriptive statistics of mean and standard deviation was used to describe the data. Results Future doctors had a mean knowledge score of 64%. Their mean knowledge scores in the nutrition topics assessed were 41% for ‘malnutrition in children’, 59% for ‘diabetes and obesity’ and 73% for ‘nutrients, energy and their deficiencies’. Future doctors’ attitudes towards nutrition care were generally positive but were uncertain in the effectiveness of health education in changing the lifestyle of patients. They felt inadequate in their self-efficacy to provide nutrition care. Attitudes towards nutrition care correlated (r = 0.371, p < 0.001) positively with self-efficacy to provide nutrition care. Level of clinical training was associated to nutrition-related knowledge of the students. Conclusion Future doctors had positive attitudes towards nutrition care but showed important knowledge gaps and also felt inadequate in their confidence to provide nutrition care. Attitudes may be important in nutrition care self-efficacy.