The aim of the study was to analyze the malnutrition risk in internal medicine patients and its impact on mortality, rehospitalization, and newly diagnosed diseases rate during twoyear follow-up. We also aimed to analyze differences in nutritional status, anthropometric, biochemical, and other clinical patient characteristics, depending on the initial hospitalization department. Total of 346 participants were included in the study, while 218 participants were followed up two years later. During the initial hospitalization, anthropometric measurements were performed (body height and weight, body-mass index, waist circumference, WHtR, upper arm circumference, skin fold thickness), nutritional risk was assessed (NRS-2002 questionnaire), biochemical parameters (glucose, CRP, creatinine, eGFR), and other clinical parameters of interest (age, sex, smoking status, chronic diseases, use of nutritional support, length of hospital stay) were analyzed. Two years later, data on mortality, re-hospitalizations, newly diagnosed diseases (diabetes, malignant disease, arterial hypertension), and the use of nutritional support were recorded. The results showed that internal medicine patients are generally old and polymorbid. As many as 38.4% of them are at-risk for malnutrition (NRS-2002≥3) during hospitalization, although their anthropometric parameters are increased. Despite the increased malnutrition risk, only 15.3% subjects were prescribed ONS during hospitalization. Followed-up, at-risk participants were more likely to be female, over 65 years of age, more likely suffered from cancer (54.9% vs. 20.6%; P<0.001), and less likely had normal renal function (eGFR≥90 ml). Anthropometric measures did not prove useful in the malnutrition assessment as 46.3% of nutritionally endangered patients proved to be overweight and obese (BMI≥25 kg/m2). In 25.6% of them, ONS was introduced during hospitalization, and 36.6% used ONS during the follow-up period. At-risk patients died significantly more often during the follow-up period (42.7% vs. 23.5%; P<0.003). Regarding anthropometric parameters, there was no statistically significant difference between participants hospitalized in different internal medicine wards, except for the upper-arm circumference (P<0.001). In patients hospitalized in Nephrology (54.5%), Hematology (45.7%), Post-Intensive Care Unit (42.9%) and Endocrinology and Diabetology (42.9%), despite the increased WHtR, a higher proportion of patients with lower and regular BMI (<18.5-24.9 kg/m2) was recorded, which can be explained as the result of sarcopenia. Also, a statistically significant differences were recorded for the value of serum creatinine level and eGFR (P<0.001), depending on the hospitalization department. At the Hematology (23.9%) and Post-Intensive Unit (42.9%), where a significant proportion of atrisk patients were hospitalized, there were patients with seemingly normal eGFR (≥90 84 ml/min) which may be explained by decreased serum creatinine level, i.e., decreased muscle mass and increased nutritional risk. There is a statistically significant difference in the frequency of rehospitalizations depending on the initial hospitalization ward (P=0.004). The initial NRS-2002 sum was correlated positively with age (r=0.471, P<0.001), sum of chronic diseases (r=0.344, P<0.001), length of initial hospitalization (r=0.249, P<0.001), and number of re-hospitalizations (r=0.198, P=0.004), while a negative correlation was recorded with BMI (r= -0.308, P<0.001), waist circumference (r= -0.188, P=0.005), and upper-arm circumference (r= -0.374, P<0.001). The initial NRS-2002≥3 was not a risk factor for rehospitalization and mortality, but it was a risk factor for newly diagnosed diseases during the two-year follow-up period (OR=5.21, 95% CI 1.38-19.75, P=0.015). The risk factor for newly diagnosed diseases was also the use of ONS during follow-up (OR=0.16, 95% CI 0.05-0.49, P=0.002). Risk factors for rehospitalization were CRP level (OR=1.01, 95% CI 1.00-1.02, P=0.032), eGFR<15 ml/min (OR=12.49, 95% CI 1.22-127.61, P=0.033) and ONS administration during the two-year follow-up period (OR=2.70, 95% CI 1.11-6.54, P=0.028). Risk factors for mortality during the two-year follow-up period were upper-arm circumference (OR=0.87, 95% CI 0.78-0.96, P=0.008) and ONS administration (OR=4.24, 95% CI 1.80-9.97, P=0.001). This study showed that a significant proportion of internal medicine patients are at an increased malnutrition risk and are not adequately nutritionally cared for. There is a difference in the proportion of nutritionally endangered patients, the use of ONS, individual anthropometric and biochemical parameters, and the frequency of rehospitalizations, depending on the initial hospitalization department. NRS-2002≥3 was not shown to be a risk factor for mortality and rehospitalization, but it was a risk factor for newly diagnosed diseases during follow-up period. Other anthropometric (upper-arm circumference) and clinical features (CRP value, ONS use) proved to be important risk factors for mortality and rehospitalization rate during the two-year follow-up period.