Aims: This prospective study was designed to determine whether ultrasound (US)-guided percutaneous fi ne needle aspiration biopsy (PFNAB)/US-guided percutaneous needle core biopsy (PNCB) of abdominal lesions is effi cacious in diagnosis, is helpful in treatment choice, to evaluate whether various other investigations can be avoided, especially invasive ones, its time (shortening hospitalization) and cost-effectiveness. Materials and Methods: A total 159 US-guided PFNAB (67) and US-guided automated PNCB (92) of abdominal lesions were performed percutaneously in 150 patients; the youngest patient was a 3-month-old female and eldest was a 75-year-old female. The patient selection was irrespective of age, sex, or location of the abdominal lesion. These patients presented with abdominal mass/lesions, suspected malignancy, jaundice, and in some cases, however, biopsy was performed to determine the nature of indeterminate lesion (malignant / benign versus abscesses). They were 47 hepatobiliary, 6 pancreas, 24 gastrointestinal tract (GIT), 20 kidneys and urinary bladder, 20 prostate, 3 lymph nodes, 4 adrenals, 8 retroperitoneal, 13 ovaries, and 9 other types of lesions. We used free-hand technique (without biopsy attachment) in 129 cases, and transrectal and transvaginal with biopsy attachment was used in 30 cases. Results: In 91.99% of cases, US-guided PFNAB/US-guided PNCB contributed signifi cantly to diagnosis in which USguided PFNAB/US-guided PNCB was the diagnostic test in 23.33% cases. It confi rmed a highly suspected diagnosis in 64% patients, and indicated a specifi c diagnosis that was not suspected in the remaining 36%. In 57.33% cases, the results of US-guided PFNAB/US-guided PNCB, did not alter treatment choice but increased physician confi dence in the choice. US-guided PFNAB/US-guided PNCB was responsible in avoiding 107 planned investigations, including 8 laparotomies, with no signifi cant complications and decreasing length of stay and resulting in 20% cost savings. Conclusions: Thus, the US-guided PFNAB/US-guided PNCB contributed signifi cantly in diagnosis, and in most of the cases it did not change treatment choice but increased clinicians confi dence in the choice. We can avoid the number of investigations, decrease morbidity and mortality, shorten hospitalization and cost by using these methods.Key-words: Biopsy, cost-effectiveness, effect on diagnosis, effect on treatment, percutaneous fi ne needle aspiration biopsy, percutaneous needle core biopsy, ultrasound RésuméObjectifs: Cette étude prospective a été conçue afi n de déterminer si l'échographie (US)-guidé percutanée fi ne aiguille biopsie d'aspiration (PFNAB) / biopsie guidée par U.S. percutanée aiguille (PNCB) des lésions abdominales est effi cacious en diagnostic, est utile dans le choix de traitement, d'évaluer si les divers autres enquêtes peuvent être évités, surtout envahissantes, son temps (raccourcissement hospitalisation) et la rentabilité.