BACKGROUND Most premature infants less than 1500 grams birth weight must be fed initially by tube because of their inability to suck effectively, or to coordinate sucking, swallowing and breathing. Milk feedings can be given by tube either intermittently, typically over 10-20 minutes every two or three hours, or continuously, using an infusion pump. Although theoretical benefits and risks of each method have been proposed, effects on clinically important outcomes remain uncertain. OBJECTIVE To examine the evidence from randomized trials regarding the effectiveness of continuous versus intermittent bolus nasogastric milk feeding in premature infants less than 1500 grams. The primary outcomes reviewed included feeding tolerance, days to reach full enteral feeding, somatic growth, days to discharge and incidence of necrotizing enterocolitis (NEC). METHODS Searches were performed of MEDLINE, CINAHL, HealthSTAR, and the Cochrane Controlled Trials Register. As well, studies identified from abstracts and conference proceedings and references from relevant publications were retrieved. METHODS Randomized and quasi-randomized clinical trials that met the following criteria for relevance: a) Enrollment of infants < 1500 grams birth weight with no major congenital anomalies which might interfere with feeding tolerance b) Comparison of continuous nasogastric versus intermittent bolus tube feedings using breastmilk or formula c) Assessment of relevant outcomes including feeding tolerance, days to full feeds, somatic growth, days to discharge, and complications such as NEC or apnea METHODS All articles retrieved from the complete search were assessed independently by the two reviewers for relevance (see selection criteria), and for methodologic quality using the following criteria: blinding of randomization, blinding of intervention, complete follow-up and blinding of outcome measurement. Only those articles judged by both reviewers to be relevant and to have appropriate methodologic quality were included in the analysis. Differences were resolved through discussion and consensus of the reviewers. RESULTS Infants fed by continuous tube feeding method took longer to reach full enteral feeds (weighted mean difference 3.0 days; 95% CI 0.7, 5.2). Although there was no evidence of a difference in the days to discharge overall, one study suggested a trend toward earlier discharge for infants less than 1000 grams birth weight fed by the continuous tube feeding method (mean difference (MD) -11days; 95% CI -21.8, -0.2). Overall, there was no evidence of a difference in somatic growth (weight, length, head circumference or skinfold thickness) between the two groups, but subgroup analyses in one study suggested that infants less than 1000 grams and 1000 - 1250 grams birthweight gained weight faster when fed by the continuous tube feeding method (MD 2.0 g/day; 95% CI 0.5, 3.5; MD 2.0 g/day; 95% CI 0.2, 3.8, respectively). There was no evidence of a difference in the incidence of NEC. One study showed a trend toward more apneas during the study period in infants fed by the continuous tube feeding method (MD 14.0 apneas during study period; 95% CI -0.2, 28.2). CONCLUSIONS Infants fed by the continuous tube feeding method took longer to reach full feeds, but there was no difference in somatic growth, days to discharge, or the incidence of NEC for infants fed by continuous versus intermittent bolus tube feeds. Small sample sizes, methodologic limitations and conflicting results of the studies to date, together with inconsistencies in controlling variables that may affect outcomes, make it difficult to make universal recommendations regarding the best tube feeding method for premature infants less than 1500 grams. The clinical benefits and risks of continuous versus intermittent nasogastric tube milk feeding cannot be reliably discerned from the limited information available from randomized trials to date.