Background: in the world, there is a significant number of people who use drugs and some of them need treatment in a care center, where they receive services that help them with their addiction problem. Objectives: through this descriptive study we studied the factors of vulnerability that influence the accessibility of people with disorders related to drug use, to ambulatory treatment services in a care center in Costa Rica. Methodology: The investigation was structured in two moments: a) between March and April of 2017, 146 outpatient users (88/60% men and 58/40% women) were surveyed in the care center, selected according to convenience criteria, their participation was anonymous and confidential; an instrument was used to collect the following data: socio-economic, geographic accessibility, economic accessibility, access to information, treatment and consumption of drugs; b) three professionals were interviewed (two in psychology and one in medicine) who work in the center of attention, to complement the results of the survey. Results: the average age of onset of substance use (alcohol, tobacco and marijuana) was fifteen years, most consumed between five and seven days a week, less than half of respondents have income (less than $ 100), there are difficulties to attend scheduled appointments due to this factor, the distance traveled, aspects of transportation, difficulty of work permits and hours of service. They emphasize the need for greater motivation, family support, the human quality of professional attention and involve the person in the planning of their treatment according to their particularities. Conclusions: Among the factors related to the people who were surveyed that affect the access to outpatient treatment services to the care center, stand out: the age of onset of consumption, the pattern of substance use, the place where they came from, the distance traveled, transportation, availability of monthly income and family support. Regarding the focus of attention, the frequency of appointment assignments, the hours of attention, the continuity in attendance at scheduled appointments that is affected by lack of motivation and the treatment received by people by professionals who are affected they attend. The care services must be designed according to the characteristics of the people who use them and information mechanisms must be promoted that encourage the use of the services of people with problematic drug use.