ABSTRACT Objective To evaluate the correlation between thickness of the muscle adductor pollicis and anthropometric measurements, body mass index and Subjective Global Assessment in the nutritional assessment of surgical patients. Methods The study population comprised patients admitted to the general and reconstructive surgery unit of a university hospital in the city of Vitória (ES), Brazil. The inclusion criteria were patients evaluated in the first 48 hours of admission, aged ≥20 years, hemodynamically stable, with no edema or ascites. Data analysis was performed using the software Statistical Package for Social Science 21.0, significance level of 5%. Results The sample consisted of 150 patients that were candidates to surgery, mean age of 42.7±12.0 years. The most common reasons for hospitalization were surgical procedures, gastrintestinal diseases and neoplasm. Significant association was observed between thickness of adductor pollicis muscle and Subjective Global Assessment (p=0.021) and body mass index (p=0.008) for nutritional risk. Significant correlation was found between thickness of adductor pollicis muscle and arm muscle circumference, corrected arm muscle area, calf circumference and body mass index. There were no significant correlations between thickness of adductor pollicis muscle and triceps skinfold and age. Conclusion The use of thickness of adductor pollicis muscle proved to be an efficient method to detect malnutrition in surgical patients and it should be added to the screening process of hospitalized patients, since it is easy to perform, inexpensive and noninvasive.