To identify and analyse the social representations (SRs) of tuberculosis (TB) among three groups of people in Medellin, Colombia, with the purpose of contributing to improvements in TB treatment and control programme activities.Cross-sectional study using free word association and evocative analysis techniques in 1049 persons within a structural SR framework.The terms 'cough', 'contagion', 'illness' and 'fear' were found to be components of the central core in the three groups. In the peripheral system, 'rejection' and 'treatment' were considered modifiable factors. Text analysis showed that 'fear' and 'compassion' are associated with evocations among patients and their relatives, 'contagion' among lay people and 'isolation' among health care personnel.Fear of infection may have a negative effect on relationships with patients, health care activities, treatment surveillance and family support for patients. A better understanding of patient beliefs and their family environment can improve treatment quality and adherence in the city.