To compare the cost-effectiveness of sacrospinous fixation (SSF) and abdominal sacral colpopexy (ASC) for posthysterectomy vaginal vault prolapse. Cost and effectiveness data for SSF and ASC were accessed from peer-reviewed literature and standard references for charges. Objective assessment of surgical cures at 36-48 postoperative months was used. Taking the perspective of a healthcare planner, the incremental cost-effectiveness ratios were calculated for both procedures. ASC is a more expensive yet more effective procedure than SSF. Compared with no intervention, SSF costs $9290 per cure. The cost per cure of ASC is $2910, compared with SSF. Under conditions of constrained monetary resources, SSF is a more cost-effective procedure than ASC. However, the decision to proceed abdominally or vaginally is more often dictated by the clinical situation and the need for ancillary repairs. © 1999 Lippincott Williams & Wilkins, Inc.