BACKGROUND Adhesion formation represents a major complication after lower abdominal operations. It is postulated that a shift in surgical practice in recent years toward the use of less invasive techniques, such as laparoscopy, may be associated with a reduction in the incidence of intraperitoneal adhesions and in the rate of adhesiolysis procedures. Using an attributable-risk methodology, this cost-of-illness study was designed to estimate the hospitalization rate and expenditures for adhesiolysis in the United States in 1994 and to examine changes in attributable expenditures since 1988. STUDY DESIGN A national hospital discharge data base was used to identify all abdominal adhesion procedures performed in the United States in 1994. Total hospitalization expenditures were based on Medicare payment rates for adhesiolysis hospitalizations and physician services, which were applied to the total number of inpatient days attributed to adhesiolysis. The results were compared with published rates and expenditures attributed to adhesiolysis in 1988. RESULTS Adhesiolysis was responsible for 303,836 hospitalizations during 1994, primarily for procedures on the digestive and female reproductive systems. These procedures accounted for 846,415 days of inpatient care and $1.3 billion in hospitalization and surgeon expenditures. CONCLUSIONS Although the adhesiolysis hospitalization rate has remained constant since 1988, inpatient expenditures have decreased by nearly 10% because of a 15% decrease in the average length of stay. The increased use of laparoscopy during this 6-year period does not appear to be associated with a concomitant reduction in the adhesiolysis hospitalization rate, suggesting that the causes of adhesion formation warrant further research.