Using data collected from a sample of 73 ISO-certified large Turkish companies, we explore the influence of various factors on large companies' satisfaction with ISO 9000. This is the first attempt to examine the relationships between companies' demographic characteristics, difficulties encountered in ISO 9000 implementation, improvements generated after attaining ISO 9000 and large companies' satisfaction with ISO 9000. Regression analysis is used to analyse the relationships between these variables. The results suggest that large companies may be more satisfied with ISO 9000 through increased emphasis on making operational improvements. In particular, they should focus on increasing product/service quality, reducing error/defect rate in production/service and achieving standardization. The paper concludes with a discussion of findings resulting in developing a model predicting companies' satisfaction with ISO 9000 and recommendations for future research areas.