Costs for reimbursement of the Integral Health Insurance (SIS) have not been studied in Peru. Objectives: To estimate the economic costs for administrative procedures for SIS reimbursement in DISA IV Lima Este during year 2002.Material and Methods: A cost study of SIS reimbursement involving a description of each activity required for reimbursement on the suppliers including time measurement, human resources required, administrative costs of reimbursement and the frequent of rejection of cases. Based on a pilot study, considering Level of Confidence: 95%, Standard error: 0.03, a sample of 60 outpatient consultations was calculated. An ad-hoc form was designed for a process analysis of SIS reimbursement for primary health care facilities (Health centers and posts).Results: Administrative costs of billing of the health consultation of SIS patient was in average 5,49 (CI 95%: 2,75 - 8,23) nuevos soles (n.s.). 100% of reimbursements lasts more than 30 days, with an average of 168 days (range: 123 - 220 days). The administrative-year costs estimated for SIS consultations at year 2002 was 1 448 251.02 n.s., amount not recognized as reimbursable at SIS. Conclusions: Costs non recognized as reimbursable are quite high and equivalent to 3 621 hospitalizations in Intensive Care Units, to 14 483 deliveries and to 10 345 cesarean sections based on SIS rates. [ABSTRACT FROM AUTHOR]