Important Factors Influencing Readiness, Barriers and Supporting Criteria for Good Manufacturing Practice (GMP) Among Pharmaceutical Manufacturers The objectives of this project were to investigate the problems and barriers in performing the GMP encountered by local pharmaceutical manufacturers ; to follow up the GMP inspection process ; and to find out the readiness and supporting criteria for conforming to the new GMP regulations. The target group of this study was 176 local modern pharmaceutical manufacturers ( 129 GMP-approved and 47 non-approved). The sample was obtained by stratified sampling technique, and the data was collected using questionnaires, interviews, focus group discussions and brain-storming processes. The GMP-approved manufacturers stated that budget was the most important factor for GMP approval ; this factor covered the cost of premises, personnel and documentation. Once the GMP was obtained, as pressure was put on those manufacturers to maintain their GMP performance, inevitably an increase of budget was required. The GMP non-approved manufacturers reported that lack of GMP consultant was the most important problem. They responded that the criteria of GMP inspection was unclear and inaccurate, since each inspector followed different standards, and this resulted in the repeated correcting of the same subject matter. About 58 % of the manufacturers agreed to have GMP enforcement so that the Thai manufacturers and Thai medicines could be upgraded to international level. Those who did not agree reasoned that the current problems or limitations regarding the GMP criteria should be solved as the first priority. Moreover, the declare of GMP regulation may bring unforeseen costs. GMP performance in the pharmaceutical manufacturers must be supported with full process i.e. problem solving and specification of development direction. The following issues should be reconsidered : reviewing of government policy relevant to international standard GMP ; import of pharmaceuticals ; promoting the pharmaceutical market nationwide and internationally ; and the roles of the Government Pharmaceutical Organization (GPO). The suggestion for further development were as follows : to set up a GMP guideline and consultant team, and to further support and assist the manufacturers to strengthen their potential in pharmaceutical exports.