This study is conducted to determine the effectiveness of Acceptance and Commitment Therapy (ACT) on mindfulness skills, thought suppression, thought control, inflexibility and valued living in patients with AIDS in Tehran. A Pretest-Posttest, two-group, quasi-experimental design is used as the research method. The study population consist of AIDS patients who referred to the clinic of research center for HIV/AIDS and sexually transmitted diseases in Imam Khomeini hospital in fall/winter 2015-16, of which 30 volunteers ( who meet the inclusion criteria, consist of: being HIV positive and consent to participate; being in age range of 30 to 58 years old) are selected and randomly divide into control and experimental groups. The questionnaire of Kentucky Inventory of Mindfulness Skills (used by Baer et al., 2004), the questionnaire of thought suppression (used by Schmidt et al., 2009), thought control questionnaire (used by Luciano et al., 2009), the inflexibility questionnaire (used by Bond et al., 2003) and valued living questionnaire (used by Wilson et al., 2010), are applied as the research tools. Data will be analyzed by Statistical Package for the Social Sciences (SPSS ver. 21).