Funding Acknowledgements Type of funding sources: None. Background/Introduction Heart failure (HF) is increasing steadily while the prognosis still stays poor despite improvements in care and availability of new therapies. The nutritional status. is important in management of HF, as an part of multidisciplinary approach. It is known that the diet depends on the availability of nutritional products and therefore also on the season. The seasonal differences of the nutritional status in HF to our knowledge has not been studied before. Purpose The assessment of variability in nutritional status among patients with heart failure with reduced ejection fraction (HFrEF) in different seasons of the year. Methods We enrolled 240 consecutive patients hospitalized at the department of cardiology, due to HFrEF with left ventricular ejection fraction (LVEF) <=40%. Patients were interviewed with MNA form to assess their nutritional status. Detailed medical history was collected. Patients were divided according to the astronomical season of the year (spring summer fall winter), depending on the time of the admission to the hospital. We compared MNA scores between mentioned groups of patients using U Mann Whitney test. Due to the possible influence of HF exacerbations on nutritional status, the second analysis was done after exclusion of patients with HF decompensation. Results Mean age was 56.4±11.3 years, 15.8 % patients were women, mean BMI – 28.8±5.5 kg/m2, mean LVEF – 23.9±7.7%, mean MNA score – 23.0±2.9 points. MNA score was higher (the sign of better nutritional status) in patients interviewed during spring compared to those assessed in summer (p=0.0094) or fall (p=0.014). The same situation was observed after the exclusion of patients with decompensation of HF: MNA score measured in patients admitted in spring was better than those hospitalized in summer (p=0.042) or fall (p=0.0064). The difference between spring and winter lacked statistical significance (p=0.058). Mean MNA scores and more important data for every season are presented in Figure 1 and 2. Conclusion(s) The differences in nutrition state in stable patients with HFrEF suggest that the seasonality of the diet might result from veritable modification in nutrition associated with availability and price of fruit and vegetables or the respondents mood, unrelated to the real nutritional status, impacts the score in the MNA questionnaire. This requires further analyses.