Quality Assurance (QA) consists of a set of activities planned and systematically implemented within the scope of the Quality System, necessary to guarantee that a process / product / system can accomplish the quality requirements. Good Manufacturing Practices are a set of procedures that aim to ensure that products are consistently produced and controlled, in accordance with the necessary quality standards. These procedures are based on national and international standards, specific to each branch of industrial activity. GMP covers all aspects of production, from inputs and raw materials, facilities and utilities to employee training and personal hygiene. Standard Operating Procedures (SOP´s) detailed written are essential for every process that may affect product quality and systems must be in place to provide documented evidence that correct procedures are consistently followed at every step of the manufacturing process. Therefore, QA incorporates the Good Manufacturing Process and other tools that aim to develop a quality product. GMP has your requirements describe in specify documents by ANVISA and they are similar as ABNT ISO IEC 17025:2017 and Good Laboratory Practices. The aim of this work was the implementation and development of Good Manufacturing Practices through a Quality Assurance System in the brachytherapy sources production on Radiation Technology Center IPEN-Brazil. First, all the production steps were defined and described in procedures, relating to the facilities and utilities necessary for this production. Consequently, the sanitization in manufacturing area was evaluated the effectiveness of different surface cleaning products, determining the best to reduce radiological contamination to acceptable levels during the sources production (iodine-125 seeds). For this, it was established a cleaning program for three production lots of iodine 125 seeds using three types of sanitizers: Extran®, hydrogen peroxide 6% and sodium hydroxide 1M. In another hand, the study of process validation was evaluated, and his parameters were: the source welding efficiency and the leakage tests results (immersion test). The welding efficiency does not have an established parameter, since is visually evaluated by the operator, and the leakage detection must be under 5 nCi / 185 Bq, accordingly with the ISO 9978. The observed values were average 79-87% production efficiency and leakage tests were under 5 nCi/seed. According to the results of sanitization, the best choice for removing the surface contamination was the peroxide hydrogen. In general, those values where were important data because they indirectly assessed all the SOP´s (standard operational procedures), equipment's, manufacturing area are following the precepts of Good Manufacturing Practices.