Problem: Although there are tools that can support the planning of assistance activities, to date there is no distribution of services health care whose organizational structure for optimal results, i.e to ensure a regular flow of patients without excessive generation of queues, with appropriate waiting times, availability of appropriate staff and strategic guidelines for specific programs, focusing on the design and organization of activities in accordance with the demand of the population served. Objective: To describe and implement a tool to model the arrival process of patients in a hospital in Colombia aimed at improving organizational management. Method: This study is an Operations Research applying a simulation model. Result: a mathematical model useful in similar contexts to generate arrivals or analysis of the influx of patients was generated.