Abstract Background: Nutrition screening using evidence-based clinical practice is important for identifying patients whose nutritional status may be compromised, so that they receive appropriate treatment. Introduction of the Malnutrition Universal Screening Tool (`MUST') in two wards in two Melbourne hospitals resulted in low screening completion rates by nursing staff. Nurses’ screening practices were explored to understand personal and workplace barriers to compliance. Methods: Surveys of patients’ medical records and focus groups with nurses were used to gather data. Audio-recorded group narratives were transcribed verbatim, and then coded thematically to develop understandings of response patterns. Results: A survey of admitted patients (n = 46) showed low screening rates by ward (17% and 62%). Eighteen nurses in two wards participated in three focus groups. The five main themes that emerged were: ‘screening role’, ‘task priorities’, ‘recognition of evidence-based practice’, ‘uncertainty of protocols’ and ‘degree of competence’. Screening completion was limited by workloads, uncertainty about screening policy and also individuals’ skill in use of the tool. Conclusions: Application of `MUST' can be facilitated by increasing nurses’ competence through training and by the provision of ongoing support. When implementing nutrition risk screening, dietitians’ roles should include continually working with nurses to identify and reduce the barriers that prevent the adoption of universal screening. Enhancement of collaboration is essential to ensure that optimal nutrition care occurs.