Abstract: The objective of the study was to analyze how stigma and discrimination manifest as barriers to effective implementation of the Teachers Service Commission (TSC) HIV and AIDS sub–sector policy among public secondary school teachers in Nairobi County, Kenya. A mixed method approach was used to collect data from public secondary teachers, Kenya Network for Positive Teachers (KENEPOTE) officials in Nairobi County and TSC officials involved in the implementation of the policy. A structured questionnaire and semi–structured interview guide were used to collect data from 202 respondents. Data was analyzed by use of descriptive statistics and formation of themes and categories. The results from the data showed that stigma and discrimination are at high levels among the secondary school teachers. As a result, HIV positive teachers have been pushed to silence. Implementation of the TSC HIV and AIDS policy has not impacted on the stigma and discrimination levels among public secondary teachers. The study recommends that ‘AIDS talk’ should encouraged among teachers by principals so as to demystify the disease hence reduce stigma and discrimination. Principals should be trained on how to handle HIV matters in schools through capacity building workshops organized by TSC. Key Words: stigma, discrimination, Teachers Service Commission, HIV and AIDS sub–sector policy