Analysing the factors and barriers associated with the population displaced by armed conflict using medical services in Bucaramanga, Colombia.Data from the "Diagnosing the health of both displaced and non-displaced populations in Bucaramanga and its metropolitan area" study, designed and executed by the Industrial University of Santander and financed by the Pan-American Health Organisation, analysed medical service use in individuals aged over 15 years. This agreed with Andersen and Newman's model and evaluated the effect of associated factors by means of multiple logistical regression.One out of each five people who became ill during the fifteen days prior to the survey had used the medical services. This percentage was smaller than that found in the Colombian population as a whole. The type of social security regime (contributory health insurance), previous service use and being from the region were associated with greater service use. Displaced people having subsidised health insurance did not present differences in service use compared to those who had no access to such insurance. The distance from dwelling to institution was another barrier against using health services (RM = 0.64; IC 0.42-0.97).There was differential medical service use amongst the displaced population, determined by their health insurance coverage and economic position.