The importance of nutrition support in intensive care has been recognised, but many factors may limit successful provision of patients' requirements. We conducted a twelve-month prospective audit, with intervention after six months, to determine whether longer-stay (> 3 days) patients in our intensive care unit were receiving their nutritional requirements and to identify and improve factors limiting nutrition provision. Data was collected for 379 consecutive patients admitted to intensive care longer than three days. Total energy provided to each patient was recorded daily and compared with the predicted requirement. In the first six months, patients commenced nutrition 2.2 +/- 1.3 days after intensive care admission and were receiving 100% of predicted energy requirement by 4.8 +/- 3.3 days. Patients received nutrition on 82.3% of total patient-days, daily average 71.7% (43.2) of their energy requirement. Nutrition was interrupted on 30% of total patient-days. After six months, a Clinical Practice Improvement model was used to analyse reasons for inadequate feeding and introduce changes in practice. Main reasons for interruption included preparation for extubation and upper gastrointestinal intolerance. After intervention, interruptions due to these reasons were significantly reduced, however, no significant improvement was observed overall, either in the time to reach nutritional goals, or in the amount of energy received. Successful changes in practice, targeting only one or two main issues, can be overwhelmed by other factors. To effect significant improvement, a wider approach may be required.