Ultrasonography (US) is becoming increasingly utilized in the United States for the evaluation of blunt abdominal trauma (BAT). The objective of this study was to assess the cost impact of utilizing US in the evaluation of patients with BAT in a major trauma center. All patients sustaining BAT during a 6-month period before US was used at our institution (Jan-Jun 1993) were compared to BAT patients from a recent period in which US has been utilized (Jan-Jun 1995). The numbers of US, computed tomography (CT), and diagnostic peritoneal lavage (DPL) were tabulated for each group. Financial cost for each of these procedures as determined by our finance department were as follows: US 96,CT494, DPL 137.Thesenumbersarerepresentativeofactualhospitalexpendituresexclusiveofphysicianfeesascalculatedin1994U.S.dollars.Costanalysiswasperformedwithttestandchisquaredtest,andsignificancewasdefinedasP3˘c0.05.Therewere890BATadmissionsinthe1993studyperiodand1033admissionsinthe1995studyperiod.Duringthe1993period,642procedureswereperformedonthe890patientstoevaluatetheabdomen:0US,466CT,and176DPL(seetable)[table:seetext].Thiscomparesto801proceduresonthe1,033patientsin1995:552US,228CT,and21DPL.Totalcostwas254,316 for the 1993 group and 168,501forthe1995group.Extrapolatedtoa1−yearperiod,asignificant(P3˘c0.05)costsavingsof171,630 would be realized. Cost per patient evaluated was significantly reduced from 285.75in1993to163.12 in 1995 (P \u3c 0.05). This represents a 43 per cent reduction in per patient expenditure for evaluating the abdomen. By effectively utilizing ultrasonography in the evaluation of patients with blunt abdominal trauma, a significant cost savings can be realized. This effect results chiefly from an eight-fold reduction in the use of DPL, and a two-fold reduction in the use of CT