Background: Adherence to antiretroviral therapy (ART) is important for effective treatment. Little is known about barriers and facilitators to ART in Zambia. The aim of the study was to gain knowledge about adherence to antiretroviral treatment among patients and health care professionals in Zambia, in order to identify interventions that may be efficient in increasing patients’ adherence to antiretroviral treatment. Methods: I conducted a qualitative study in Kitwe and Masaiti districts on the Copperbelt Province of Zambia in 2006. I used a combination of in-depth individual interviews and focus groups with patients on ART, health care professionals working in ART clinics and other informants. The material was analysed using qualitative methods. Results: My study identified barriers and facilitators which were diverse in nature and belonged to a wide spectrum of factors which include patient related, health service related, socioeconomic and cultural factors. These include lack of communication and information about ART, inadequate time during consultations, follow up and counselling, forgetfulness, stigma, discrimination and disclosure of HIV status, lack of confidentiality in the treatment centres, lack of nutritional support, feeling better, prospects of living longer, family support, information about ART, support for income generating activities and transport.. Conclusion: This study suggests a multiplicity of factors and issues which need to be taken into consideration when providing ART. Further research is needed including participant observations to capture the actual interactions between patients and their health care providers. Also, future studies should assess the magnitude of non adherence to ART in Zambia using quantitative measures. My findings can inform the design of interventions to promote adherence to ART