Background: To identify the optimal cost effective strategy for the management of women having ASC-USwho attended at King Chulalongkorn Memorial Hospital (KMCH). Design: An Economical Analysis based ona retrospective study. Subject: The women who were referred to the gynecological department due to screeningresult of ASC-US at King Chulalongkorn Memorial Hospital, a general and tertiary referral center in BangkokThailand, from Jan 2008 - Dec 2012. Materials and Methods: A decision tree-based was constructed to evaluatethe cost effectiveness of three follow up strategies in the management of ASC-US results: repeat cytology, triagewith HPV testing and immediate colposcopy. Each ASC-US woman made the decision of each strategy afterreceiving all details about this algorithm, advantages and disadvantages of each strategy from a doctor. The modelcompared the incremental costs per case of high-grade cervical intraepithelial neoplasia (CIN2+) detected asmeasured by incremental cost-effectiveness ratio (ICER). Results: From the provider’s perspective, immediatecolposcopy is the least costly strategy and also the most effective option among the three follow up strategies.Compared with HPV triage, repeat cytology triage is less costly than HPV triage, whereas the latter providesa more effective option at an incremental cost-effectiveness ratio (ICER) of 56,048 Baht per additional case ofCIN 2+ detected. From the patient’s perspective, the least costly and least effective is repeat cytology triage.Repeat colposcopy has an incremental cost-effectiveness (ICER) of 2,500 Baht per additional case of CIN2+detected when compared to colposcopy. From the sensitivity analysis, immediate colposcopy triage is no longercost effective when the cost exceeds 2,250 Baht or the cost of cytology is less than 50 Baht (1USD = 31.58 THB). Conclusions: In women with ASC-US cytology, colposcopy is more cost-effective than repeat cytology or triagewith HPV testing for both provider and patient perspectives.