Objective: to establish the magnitude of hospital rehospitalizations and its relationship with prognostic factors including demographic and clinical characteristics and costs, between the members of Organizacion Sanitas Internacional in Colombia. Methods: analytical study of a retrospective cohort, which included 77.615 patients hospitalized between January 1, 2008 and January 31, 2009. Results: readmission probability at 30 days was 9.3%, after 60 days it was 12.1% and after 90 days it was 13.9%. We found a higher number of rehospitalizations in men and in those over 65 years. The diagnoses related with hematological diseases, circulatory system diseases and neoplasms were those that presented the highest values of relative risk for readmission (14,5, 7,9 and 7,8, respectively). The average hospital stay of readmissions within 30, 60, and 90 days was greater than the one of patients not readmitted (6.71 vs. 4.08 days, p.