BACKGROUND: The 21st century Influenza A (H1N1) pandemic arrived during spring of 2009 and has posed a serious public health challenge world-wide. We describe the clinic-radiological profile and outcome of patients who were found H1N1 positive in Jawahar Lal Nehru Hospital, Ajmer of Rajasthan from 5th August 2009 to 31st May 2014. AIMS AND OBJECTIVES: Primary objective was to study clinical and radiological profile of the patients admitted with confirmed H1N1 infection. Secondary objective was to observe the risk factors and associated comorbid conditions with complications and need of mechanical ventilation and / or death among H1N1-infected patients MATERIALS AND METHODS: Hospitalized patient with laboratory-confirmed H1N1 flu by reverse transcriptase PCR during August 2009 to May 2014 in JLN Hospital, Ajmer, were included in this retrospective study. Data was collected from hospital isolation ward admission register. Statistical analysis was done by SPSS, version 16. Binary logistic regression was used to find out independent risk factors for morbidity. RESULTS: A total of 94 PCR-confirmed H1N1-infected patients were included in the study, of them 32 (34%) males and 62 (66%) females. Median age was 35 years and median duration of symptoms before hospitalization was 5 days. Common presenting symptoms include fever 83 (88%), cough 79 (84%), breathlessness 67 (71%), rhinnorrhoea/ common cold 25 (26.5%), throat pain 13 (13.8%), chest pain 5 (5.3%) and haemoptysis 4 (4.2%). Bilateral crepitations were audible in 86 (91.4%) and tachypnoea in 73 (78%) cases. Co-morbidities were seen in 75 (79.7%) patients. Ventilatory support was required in 57 (60.6%) patients. On presentation, chest x-ray showed pulmonary opacities in 72 (76.5%) patients. We observed no significant side effects of oseltamivir 150 mg twice day dose for 5-7 days. Forty-one (43.6%) patients were cured and discharged from hospital, 53 (56.3%) patients died. Development of ARDS, involvement of bilateral lower zones of lungs in chest skiagram, requirement of mechanical ventilator and associated pregnancy (third trimester) were independent predictors of mortality. CONCLUSION: During evaluation period from 2009 to 2014, H1N1 influenza caused severe illness requiring hospitalization, including pneumonia, acute respiratory distress and complications involving renal, liver and cardiac dysfunction. Maximum patients were between age group of 20-40 year. Fever and cough were most common presenting symptoms. Common comorbidities were pregnancy, diabetes, hypertension, and obesity. Mortality rate was high in H1N1-infected patients with development of ARDS, associated pregnancy and patients who required ventilatory support.