Abstract Background Malnutrition can affect the clinical course of hospitalized patients, increasing hospital stay, infections, mortality, and hospital costs. Among heart disease patients, the malnutrition prevalence ranges from 25 to 51.9%. Objective To assess the prevalence of malnutrition and its association with clinical complications in cardiac patients admitted to a cardiology hospital. Method Retrospective cohort study with patients evaluated within 48 hours of admission to the ward of a referral center for cardiology in Porto Alegre, Brazil. Patients were aged 18 years or older. Malnutrition was assessed by Subjective Global Assessment. Length of hospital stay, transfer to the intensive care unit (ICU), hospital discharge and in-hospital death were collected from medical records. Statistical analysis was performed using the SPSS 22.0 program. Comparisons between groups with and without malnutrition were made by unpaired Student's t-test and chi-square test with adjusted residuals, and multivariate Poisson regression used for analysis of outcomes. The significance level considered was 5%. Results We evaluated 130 patients aged 63 ± 13 years, 63% were male, and the most frequent cause of hospitalization was angina (25%). The prevalence of malnutrition was 27% and, after statistical adjustment for age, malnutrition was positively associated with ICU transfer and length of hospital stay longer than seven days. Conclusion The prevalence of malnutrition found in this sample was 27% and this nutritional diagnosis was positively associated with ICU transfer and length of hospital stay longer than seven days. (Int J Cardiovasc Sci. 2020; [online].ahead print, PP.0-0)