Background: The staff of the Office of Disease Prevention and Control 4, Saraburi, Department of Disease Control, Ministry of Public Health, Thailand analyzed the data of 28 cases of diagnosed silicosis (J62.8) whose data were reported to the Health Data Center in Saraburi province, Thailand. Thus, its staff in collaboration with the staff of the Bureau of Occupational and Environmental Diseases, Department of Disease Control, Ministry of Public Health, Thailand formed the outbreak investigation team for this epidemiological outbreak of silicosis in Saraburi province, Thailand and operated from May 15, 2017 to May 17, 2017. Objective: 1. To confirm the diagnosis of Silicosis. 2. To find the causes of Silicosis. 3. To advice the health-care issues for Silicosis prevention to all patients diagnosed of Silicosis including high-risk populations of Silicosis Methodology 1. Meeting with stakeholders at Saraburi Hospital. This aimed to examine diagnostic Criteria from medical records in Saraburi Hospital and to define the definition of patients and suspected patients with Silicosis as well as organizing an investigation team. 2.Investigated suspected patients with Silicosis by using the clinical criteria which was provided by Saraburi Provincial Public Health Office, the Office of Disease Prevention and Control 4, Saraburi, Saraburi Hospital as well as the Health Promoting Hospitals.3.Meeting of a summarizing the investigation and root cause analysis regarding Silicosis with the Bureau of Occupational and Environmental Diseases, Saraburi Provincial Public Health Office and the Office of Disease Prevention and Control 4, Saraburi at Saraburi Hospital as well as planning for a surveillance system. Results: From analysis of 28 cases registered in Health Data Center, Saraburi province, Thailand by the outbreak investigation team, there were one case with no data availability, three cases with non-classification of suspected Silicosis, and 24 cases of suspicion criteria. Out of 24 Silicosis suspected cases, 8 cases were unable to follow up due to their homes being out of the Health Inspection Region 4, one case died of Nocardia species infection, one case of not being occupational cause, and one case of refuse to provide personal health data. Thus, only 13 cases were eligible for study. Of 13 cases, 12 cases were diagnosed of chronic Silicosis whereas one case was not compatible with the diagnostic criteria. Conclusion: As a result of the investigation of 13 cases, 12 cases were diagnosed as chronic silicosis. The main cause of silicosis in this study population was receiver, whereas the secondary causes were source and passage.