Aim: The aim of our study was to evaluate a hypercaloric sweet milk-based oral nutrition supplement in a prospective 3-day study designed to assess the taste preferences of this oral nutritional supplement (ONS) in malnourished inpatients and the influence on adherence in daily intake. Methods: A total of 46 in patients with recent weight loss were included in this study. One flavor (chocolate, vanilla or strawberry) was administered each day in a random way to each patient during 3 consecutive days. In the first 3 days, patients were asked to fill 2 questionnaires intended for reflecting ONS tolerance and acceptance. Results: Sweet was better for chocolate flavor (3.9 ± 2.4 points) than for vanilla flavor (2.7 ± 2.3 points; p < 0.02) and strawberry flavor (3.1 ± 2.3 points; p < 0.01). Chocolate flavored ONSs were rated as having more aftertaste (3.4 ± 2.1 points) than vanilla (2.4 ± 2.1 points; p < 0.01) and strawberry (2.6 ± 1.5 points; p < 0.03). Patients who chose chocolate took a total of 20.7 ± 20.9 average bricks during hospitalization (1.95 ± 0.2 per day), patients who chose vanilla took 18.6 ± 21.0 bricks (1.90 ± 0.7 per day) and finally patients who chose strawberry took 14.5 ± 13.5 bricks during admission (1.78 ± 0.1 per day; p < 0.01). Conclusions: The taste preferences of all the ONSs are similar although the consumption is high in chocolate flavored ONS during hospitalization. Sweetness may have influenced this finding.