Objective To investigate the risk factors for in-hospital pulmonary infection in senile hip fracture population. Methods A retrospective cohort study was performed in 1,419 hip fracture patients older than 50 years old who had been consecutively admitted to our department from January 2000 to October 2011. They were 545 men and 874 women, aged from 50 to 102 years. They were divided into 2 groups according to presence or absence of in-hospital pulmonary infection. There were 72 cases (5.1%) in the infection group and 1,347 cases (94.9%) in the non-infection group. The 2 groups were compared in terms of surgery related factors, like age, fracture type, American Society of Anesthesiologists (ASA) grading and anesthesia, and complications of different systems, anemia, and levels of serum proteinemia and creatinine. Candidate risk factors were evaluated by Logistic regression model to screen specific risk factors for in-hospital pulmonary infection. Results After confounding factors adjusted, woman (OR=1.764, P=0.048), old age (OR=1.697, P=0.002), ASA grade Ⅲ or above (OR=3.068, P< 0.001), general anesthesia (OR=3.773, P=0.038), anemia (OR=2.603, P=0.002), hypoproteinemia (OR=1.914, P=0.019), high creatinine (OR=3.289, P=0.014), chronic obstructive pulmonary disease (COPD) (OR=2.382, P=0.049), and tumor (OR=2.599, P=0.042) were all independent risk factors for in-hospital pulmonary infection in senile hip fracture patients. Conclusion In addition to conventional treatment, senile hip fracture patients should be given other interventions, such as correction of hypoproteinemia and anemia, and specific treatment of COPD, in order to reduce the incidence of in-hospital pulmonary infection and to improve prognosis. Key words: Hip; Fractures, bone; Risk factor; Pneumonia