LGBT+ workers are invisible in Turkish work life. This paper aims to investigate LGBT+ workers as internal customers and how their performance in the workplace is affected by minority stress. Since LGBT+ individuals face covert discrimination in the workplace, this might cause minority stress. According to this argument, this study will investigate whether minority stress causes performance loss in the workplace and whether this affects LGBT+ people's performance as internal customers. Grounded theory approach has been used in this research. To conduct the qualitative study, 36 phone interviews were conducted. Participants were recruited with the snowball sampling method. The interview form was prepared according to the Human Rights Campaign’s Corporate Equality Index questionnaire and included a video that shows a job interview. Based on the results, minority stress causes performance loss in the workplace. The findings highlight that LGBT+ individuals generally prefer not to be out at their workplaces because of internalized homophobia, perceived stigma, and prejudiced events concerning their sexual identity and gender expression. Furthermore, nondiscrimination is not legally enshrined in Turkey. LGBT+ individuals face covert discrimination in the workplace, which affects their performance as internal customers. Only a few Non-Governmental Organizations have reported on LGBT+ individuals’ working situation. This research paper comprehensively examines their work lives and attitudes towards companies. Keywords: LGBT+, internal customer, minority stress, gender, workplace