The study aimed to clarify how to increase the amount of drug produced by the availability of raw materials required for manufacturing, prevent manufacturing errors, and improve environmental efficiency and effectiveness, which leads to increased profitability by relying on the application of the six sigma methodology by integrating the dimensions of the six sigma methodology into the dimensions of supply chains and its impact on improving performance. environmental companies in the pharmaceutical sector in the public business sector, and the total number of forms that were distributed was 361 forms, and the total number of forms that were returned was 326 forms, and the percentage of the total refund was 90.31% of the total number of forms distributed, and the number of forms distributed was as follows (44) senior management, (71 (middle management), (246) executive management. The study belongs to descriptive analytical research. Where the questionnaire was used as a basic tool for data collection after preparing a survey list consisting of a set of questions that were directed to the research sample (senior management, middle management, executive management) with the aim of identifying their opinions, and analyzing them to find out the impact of applying the Six Sigma methodology on supply chains to improve environmental performance. The research sample (employees of pharmaceutical companies in the public business sector in various job grades) for the purpose of knowledge and benefit from their opinions to measure the extent of application of the Six Sigma methodology and its impact on supply chains to improve environmental performance; With (361) questionnaires, (44) senior management, (71) middle management, (246) executive management. The study reached several results. Among the most important of them: There is a significant impact of the dimensions of the Six Sigma methodology on the environmental performance of the companies producing medicines in the public business sector through the mediation of supply chains as an intermediate variable in the companies producing medicines in the public business sector under study.