Between February 1992 and July 1995, we performed 222 ultrasound-guided fine-needle aspiration biopsies (FNAB) in abdominal space-occupying lesions. The sensitivity was 90% and the specificity, 100%, with an overall diagnostic precision of 93%. We also determined the cost of each procedure (2,550 pesetas) and compared it with the cost of computerized tomography (CT)-guided biopsy (22,500 pesetas). These results and those reported in the literature indicate that there is no significant difference with respect to diagnostic yield, but that the difference in terms of expense is considerable. We believe that, in the assessment of abdominal lesions. CT-guided FNAB should be reserved for those lesions that prove inaccessible to ultrasound.