Objective: To assess tolerance of intragastric enteral nutrition started within 24 hours of admission to an intensive care unit (ICU). Design: A prospective cohort study. Setting: A medical/surgical university-affiliated ICU. Subjects: We evaluated 73 consecutive eligible patients with an expected length of stay and anticipated intolerance to oral nutrition of more than three days. We enrolled 45 patients (27 [60%] male), aged 55.4±19.0 years with a mean Simplified Acute Physiology Score (SAPS) of 11.0±4.3. Admitting diagnoses included medical (n=16), trauma (n=13), neurosurgical (n=12) and neurological (n=4) conditions. Interventions: We utilised a protocol in which intragastric feedings were initiated at 10 ml/hr within 24 hours of admission, checking gastric residuals every 4 hours. Every 12 hours, the rate was increased by 25 ml/hr if the residual volume was 200 ml and accompanied by nausea, vomiting or abdominal distension, feeds were discontinued for 4 hours then reassessed. Endpoints: Time to initiation and tolerance of enteral nutrition. Results: Forty-five patients were started on enteral nutrition 16.4±7.9 hours after admission. Eleven of 45 patients (24%) failed early intragastric enteral nutrition (six had persistent high gastric residuals, four vomited, and the protocol was not implemented in one). Nineteen of 45 patients (42%) achieved tolerance at 3.8±1.6 days post-ICU admission. Conclusions: Early intragastric enteral nutrition is tolerated in some critically ill patients. High gastric residuals limit the success with early feeding.