BACKGROUND: Growing requirements to train more dietetic students greatly increase the teaching burden on clinical supervisors. This may be reduced if students can develop basic nutrition assessment skills before they commence clinical placement. To test achievement of these skills by Australian dietetic students, a preclinical objective structured clinical examination (OSCE) was developed. Performance at this OSCE was then compared with the performance at first clinical placement. METHODS: An OSCE was developed to test preclinical skills during the third year of a 4-year dietetic degree. Learning outcomes relating to nutritional assessment skills were assessed via a 1-h preclinical examination. Student application of these skills was then assessed after the first clinical placement, when performance was compared with the results at the preclinical OSCE. RESULTS: One hundred and ninety-three students completed the preclinical OSCE and first clinical placement during the period 2002-2007. A strong relationship was observed for individual student scores at the OSCE and the score achieved at the end of clinical placement (beta = 0.66; 95% confidence interval = 0.46-0.86; P < 0.0001). This relationship was maintained even when outliers were removed. No specific year effect was apparent. CONCLUSIONS: A third-year preclinical dietetic OSCE was found to be a valuable method of formative assessment for assisting dietetic students with the preparation for their first clinical placement. It aided the early identification of those students who are likely to do less well on their first clinical placement.