Objective To analyze the epidemiological features of hemorrhagic fever with renal syndrome (HFRS) and associated environmental risk factors for HFRS and associated environmental risk factors for HFRS in Liaoning province, China during 2005-2007, and to provide a scientific basis for HFRS control measures. Methods The epidemic data of HFRS in Liaoning province were collected. Analysis was performed to determine the correlation between the epidemic features of HFRS and environmental factors such as mean temperature, relative humidity, rainfall, sunshine, urban rodent density, rural rodent density, and virus?carrying rate. Results There were 7298 cases of HFRS in Liaoning province from 2005 to 2007, and 78 of them died. The mean annual incidence of HFRS was 5.78/100 000, and the mortality was 0.06/100 000; the incidence and mortality were higher in males than in females; 59.55% of the cases and 69.23% of fatal cases were aged 35-60 years; 61.98% of the cases and 56.41% of fatal cases were farmers. The peak of incidence appeared mainly in November to January and March to May, while the trough period was in July to October, showing the seasonal characteristics in mixed epidemic area; the mean annual incidence of HFRS was relatively high in the cities of Benxi (13.70/100 000), Huludao (12.92/100 000), Jinzhou (11.30/100 000), Dandong (10.21/100 000), and Fushun (9.84/100 000). The incidence of HFRS was negatively correlated with temperature but positively correlated with rainfall, rural rodent density, and virus-carrying rate; the Spearman rank correlation coefficients were -0.351, 0.400, 0.449, and 0.377, respectively, and the P values were 0.023, 0.009, 0.003, and 0.016, respectively. Conclusion In Liaoning province, HFRS is prevalent mainly in winter and spring and among young male farmers. The prevalence of HFRS is closely related to temperature, rainfall, rural rodent density, and virus-carrying rate in the same year.