Objective: To assess the clinical practice, barriers, and facilitators in promoting smoking cessation in primary healthcare clinics in Mexico City. Materials and methods: A mixed method design was used. Surveys (n = 70) and semi-structured interviews (n = 9) were conducted with health personnel involved in smoking cessation clinics. Results: Quantitative data revealed that physicians were more likely than nurses to 1) ask patients if they smoke (57.9% vs 34.5%, p = .057), 2) ask patients if they are interested in quitting smoking (65.7% vs 26.9%, p = .003), 3) provide advice to quit smoking (54.3% vs 29.2%, p = .056), and 4) assess whether pharmacotherapy is needed (21.9% vs 10%, p = .285). Qualitative data showed that nurses were more likely than physicians to report lack of resources to refer patients to smoking cessation services, lack of pharmacotherapy availability, and lack of provider training in smoking cessation. Reported barriers include lack of motivation among patients, lack of time for assessment, long appointment wait times, and lack of training. Reported facilitators include existence of smoking cessation programmes and pharmacotherapy at no cost to the patient, and having a multidisciplinary team. Conclusions: Due to numerous barriers, smoking cessation interventions are partially implemented in primary care clinics in Mexico City. A restructuring of services is necessary, and nurses should be given a more prominent role.