A dietary interview performed by expert personnel is considered to be the most appropriate tool to check whether patients with coeliac disease follow a strict gluten-free diet. However, we currently have no straightforward and non-subjective method for performing such a dietary interview. We therefore developed a fast questionnaire based on four simple questions with a five-level score (0-IV). To verify whether our questionnaire is an efficient tool, we applied it to 168 coeliac patients (126 females and 42 males; mean age 42.4 (SD 12.9) years) on a gluten-free diet (median 82, 25th-75th percentile 50-108, range 15-389 months). The score we obtained was compared with the persistence of both villous atrophy and endomysial antibodies while on a gluten-free diet. A comparison with survival of the patients was also performed. Patients were interviewed over the phone by non-expert personnel. The questionnaire was completed in less than 1 min. The lowest results were significantly more frequent among the patients with a persistence of both villous atrophy and positive endomysial antibodies. Death risk was also significantly correlated with the lowest score results. We conclude that our questionnaire is a reliable and simple method of verifying compliance with a gluten-free diet.