Objective: To analyze fall risk factors in the first 48 hours of hospitalization and to associate them with the occurrence of falls. Method: Cohort study conducted at a hospital in Porto Alegre/RS, Brazil. A sample of 556 patients from an adult in-patient study population were evaluated within the first 48 hours of hospitalization for factors associated with falls, based on the Morse Fall Scale (MFS) and muscle strength, among others. Results: Evidence showed that the classification of high-risk according to the MFS and, more specifically, the items history of falls, ambulatory aid, impaired gait and overestimation of walking ability, were associated with falls during hospitalization (p≤0.005). In addition to these risk factors, reduced muscle strength and visual deficit also contributed to the occurrence of this safety incident. Conclusion: The analysis of fall risk factors in patients evaluated within 48 hours of hospitalization may contribute to minimizing these occurrences and preventing injury.