Routine endoscopic ultrasound (EUS)-guided biopsy of the pancreas typically utilizes fine-needle aspiration (FNA) to acquire a sample for cytologic analysis. The development of EUS-guided FNA biopsy techniques, which aims to obtain a histological core of tissue, has many potential benefits compared with EUS-FNA. The goals of this review are to review the need, indications, and techniques for EUS-FNA biopsy and review the current literature as it pertains to pancreatic disease.A 64-year-old man presented for evaluation of vague abdominal pain. Initial liver chemistries and CA-19-9 levels were normal. Computed tomography scan of the abdomen revealed a diffusely swollen pancreatic body and tail without a distinct mass. Given the suspicion for a benign pancreatic condition, endoscopic ultrasound evaluation was requested. At the time of endoscopic ultrasound, a diffusely hypoechoic pancreatic parenchyma with hyperechoic foci and irregular pancreatic duct intermittently was noted suggestive of chronic pancreatitis. Endoscopic ultrasoundguided fine-needle aspiration biopsy (EUS-FNAB) with 19-gauge TruCut biopsy (TCB) needle (Quick-Core; Wilson-Cook, Winston-Salem, NC) was performed 3 times with 2 cores of tissue retrieved and submitted for pathologic evaluation.All biopsies cores underwent routine histological processing of formalin fixation and paraffin embedding in a single block. Initial hematoxylin-eosin (H&E) levels revealed evidence of chronic pancreatitis, with features compatible with autoimmune pancreatitis (AIP) in the 1 visible core (Figs. 1A and B). However, additional deeper H&E levels revealed diagnostic evidence of invasive ductal adenocarcinoma in the second core, not present on initial levels (Figs. 1C and D). The patient subsequently underwent exploratory surgery within 2 weeks of the initial EUS evaluation, and the primary pancreatic ductal adenocarcinoma was deemed unresectable because of the presence of liver metastases.The current diagnostic yield for EUS-FNA cytology of pancreatic masses is high, better than for nonpancreatic indications, but not perfect. 1-5 There are several reasons for the suboptimal diagnostic results including variable operator-dependent EUS imaging and techniques, the lack of local available cytologic expertise, poor specimen cellularity, and lack of detail on the tissue architecture and morphology. This latter issue is particularly problematic for separating out well-differentiated pancreatic ductal adenocarcinoma from normal pancreatic tissue, as well as trying to diagnose pancreatic malignancy in the setting of chronic pancreatitis. 6,7 For example, it is very difficult to make a diagnosis of AIP using cytology alone, and the available histology allows for not only architecture but also semiquantitative immunohistochemistry (IHC) with immunoglobulin G4