Leprosy is an illness of high prevalence in the North region of Brazil and Rondônia is one of the most affected States; the medical treatment is one of the ways to prevent the illness to spread, therefore it?s important to close the infection source. The present work intended to draw the demographic profile of those people who have abandoned the treatment, to investigate the causes of this abandonment and to consider solutions to decrease the number of people who give up having the medical treatment. The demographic and the illness situation of 966 infected people were analyzed. 73 of them had abandoned the multichemical treatment. Through interviews, the information on the abandonment was raised and grouped. These infected people show the multibacillary form of the illness being the most common dimorfa. The great majority does not know the etiologic agent and the people get infected. Three groups were formed according to cause of the declared abandonment. The first one presents strong negation of the illness, the second is represented by people that had significant interruption in their daily routine due to the beginning of the treatment, which influenced their lives in a negative way mainly at work, and the third group comprehend people that have abandoned the treatment for reason as forgets, alcoholic drinks or for the fact of no more filling illness symptom . The decentralization of services, the feeding of the data base on the patients, and intensification of the search of the abandonment cases and the betterment of quality services redered are needed measures to get better results and consequently cut down the cases of Hansen disease in the city.