Background and aims <p>Mechanically ventilated patients in intensive care units frequently require enteral nutrition. The choice of an appropriate feeding method may significantly influence nutritional status and clinical outcomes. Among biomarkers used for nutritional assessment, serum albumin, and prealbumin are widely accepted as reliable indicators for evaluating the effectiveness of nutritional interventions. This study aimed to compare the effects of two common enteral feeding methods—bolus and continuous feeding—on serum albumin and prealbumin levels in mechanically ventilated ICU patients.</p> Methods <p>This parallel, single-blind clinical trial was conducted at Imam Khomeini Hospital in Tehran, Iran, with 34 ICU patients receiving mechanical ventilation. Participants were randomly assigned to either the continuous feeding group (Intervention, <i>n</i> = 17) or the bolus feeding group (Control, <i>n</i> = 17). Enteral feeding was delivered via a nasogastric tube for one week. Serum albumin and prealbumin levels were measured before and one week after the intervention. Data were analyzed using SPSS version 16, and hypotheses were tested using paired and independent t-tests.</p> Results <p>No significant changes were observed in serum albumin levels within or between the groups over the intervention period. However, patients in the continuous feeding group (Intervention group) showed a statistically significant increase in serum prealbumin levels (from 0.11 ± 0.06 to 0.15 ± 0.02&#xa0;g/L, <i>p</i> = 0.004). In contrast, the change in the Bolus feeding group (Control group) was not significant (from 0.10 ± 0.04 to 0.12 ± 0.06&#xa0;g/L, <i>p</i> = 0.39). The between-group comparison of post-intervention prealbumin levels approached significance in favor of the continuous feeding group (<i>p</i> = 0.08).</p> Conclusion <p>Continuous enteral feeding may have a positive effect on serum prealbumin levels in mechanically ventilated patients, while bolus feeding showed no such impact. However, due to the small sample size and short duration of the intervention, these findings should be interpreted cautiously. Further research with larger sample sizes and longer follow-ups is needed to confirm these results (Fig.&#xa0;1).</p> Trial registration <p>The protocol of this clinical trial has been registered in the Iranian Clinical Trial Registration Center (registration code: IRCT20190128042528N1). Registered 18 January 2020- Retrospectively registered, date of first recruitment: 6 October 2018, <a href="https://www.irct.ir/">https://www.irct.ir/</a>.</p>