['Controversy exists over whether or not single-needle liver biopsies are sufficient to compare histological parameters in patients with non-alcoholic fatty liver disease.', 'To identify sampling variability, we biopsied four liver specimens per patient, based on biopsy size (needle vs wedge) and location (left vs right lobe), immediately prior to bariatric Roux-en-Y gastric bypass surgery.', "Ten prospectively enrolled, morbidly obese patients underwent 40 laparoscopy-guided biopsies; two needle and two wedge from each of 16 left and 16 right liver lobes. The Kappa coefficient for concordance compared histological parameters from left and right lobe needle- and wedge biopsies. Wedge biopsies were considered our 'Gold Standard'.", 'Each patient had two wedge- and two needle liver biopsies. Kappa concordance between all needle and wedge biopsies from right and left lobes showed variability. Wedge- and needle liver biopsies from contralateral lobes had higher concordance with each other, compared to ipsilateral needle/wedge biopsy pairs. Contralateral wedge pairs had higher concordance than contralateral needle/needle pairs. There were no biopsy complications.'] Do wedge and needle liver biopsies show discordant histopathology in morbidly obese patients undergoing Roux-en-Y gastric bypass surgery?