S U M M A R YWith the aim to analyze the clinical manifestations and outcomes of influenza, we evaluated the symptoms of proven H1N1 cases and outcomes of patients admitted to hospitals Babol University of Medical Sciences during 2015 -2016.In this descriptive cross-sectional study, we included patients diagnosed with influenza-like illness (ILI) from October 2015 to March 2016 at hospitals affiliated to Babol University of Medical Sciences.To diagnose H1N1 infection, reverse transcription-polymerase chain reaction (RT-PCR) was performed on nasopharyngmeal swabs collected from the patients.In the current study, 123 patients were admitted due to ILI.The RT-PCR result was positive in 47.2% of patients. Symptoms such as productive cough (35.3%), sore throat (51.4%), headache (50%), dyspnea (53.2%) were comparable between PCR + H1N1 confirmed cases and H1N1 negative cases. Among the H1N1 confirmed cases, 48.3% were admitted to the intensive care unit (ICU) because of the disease severity, and 20.7% died even after receiving the therapy for several days. Among the infected cases, 20 women were pregnant, out of which three subjects died. Mortality was mostly observed in the age ˃ 50 (39%) (p = 0.03). Myalgia was significantly less observed in the group with mortality compared to other age groups (6.5% vs. 93.5%) (p = 0.005). The mortality rate of patients who received vancomycin was found to be significantly low (40%) (p = 0.01). In mortality group, the frequency of patients with creatinine levels > 1.5 mg/dL was significantly higher (58.3%) (p = 0.009) than in the group of patients who recovered. The average length of hospitalization in the mortality group was significantly longer than the hospitalization of the recovered group (11.1 days vs. 6.3 days) (p = 0.02).The current study reported a mortality rate that was more than expected in comparison to previous seasons. Our study results suggest that the absence of typical influenza symptoms such as myalgia should not cause a O r i g i n a l a r t i c l e Acta facultatis medicae Naissensis 2019; 36(4):356-364 357 delay in the diagnosis of this infection in cold seasons.