This cross-sectional study investigated the relationship between Oral Assessment Guide (OAG) scores and malnutrition in newly hospitalized patients. A total of 880 hospitalized adults were enrolled. Hypoalbuminemia was defined as serum albumin less than 3.5 g/dL. Patients with hypoalbuminemia were older (P < 0.001), had a higher prevalence of respiratory diseases (P < 0.01), a higher prevalence of digestive diseases (P < 0.01), a lower prevalence of oral feeding (P < 0.001), a lower body mass index (P < 0.001), and higher OAG scores (P < 0.001) than those without hypoalbuminemia. Multivariate logistic regression analyses showed that the prevalence of hypoalbuminemia was significantly related to age (odds ratio [OR] = 1.05, P < 0.001), absence of oral feeding (OR = 2.72, P < 0.001), presence of respiratory diseases (OR = 2.53, P < 0.01), presence of digestive diseases (OR = 1.64, P < 0.01), and OAG scores (OR = 1.14, P < 0.01). Regarding OAG scores, the OR of hypoalbuminemia was greater in patients with disorders (scores 2 or 3) of swallowing (vs. score 1, OR = 1.83, P < 0.05) and saliva (vs. score 1, OR = 1.51, P < 0.05). There appears to be a positive association between OAG scores and hypoalbuminemia in hospitalized patients.