Group occupational health service programme started in 1990 is one of the measures to cope with limited human and financial resources in occupational health. The programme has expanded rapidly to include 52 institutions, private as well as public, all over the country. In spite of its potential impact on health of employees and practice of occupational health in small and medium sized industries, comprehensive evaluation in terms of quality has not been tried. This study has aims to develop the criteria to assess the quality of newly developed group occupational health service programme, and to investigate the quality of institutions, and finally to develop policies for the quality improvement. 1) Criteria development : By defining occupational health services, in particular for small and medium sized industries, as one of the primary health care, followings are included as core elements of qualitative occupational health programme ; accessibility, continuity, comprehensiveness, technical quality, intersectoral collaboration, emphasis on preventive services, community participation, and adequacy. Again each element is divided into five major components of national health system infrastructure developed by the World Health Organization ; development of health resources, organized arrangement of resources, delivery of health care, economic support, and management. In turn, each component is categorized into three aspects of quality assessment, structure, process and outcome. Expert panel selected several criteria for each category to evaluate the programme. Criteria were modified according to each group of interviewees, to produce two sets of questionnaire, one for chief operating officer and another for nurses in the institutions, and the chief operating officer and workers in the workplace. 2) Subject : Of all 52 institutions, 25 voluntarily participated in the survey. At individual institution, chief operating officer and practicing nurses were interviewed in depth. After intensive education for interviewees, every interview was performed with standardized guideline and questionnaire. The quality of the 'Group occupational health service programme' was found to be lower than expected. Especially In continuity, comprehensiveness, technical quality, community participation and adequacy, lower quality in structural aspect was commonly identified throughout all the institutions. Quality in terms of accessibility and continuity highly varied among institutions. To improve quality of the programme, more comprehensive and systematic programme such as accreditation has to be introduced. In addition, human resources, governmental fund and information systems for individual workers are to be developed. As a long range plan, integration of occupational health services into the national health systems and pooling of financial resources and planned allocation should be considered.