Objective To describe and increase understanding of the brachial-basilic vein anatomy that could impact planning of long-term hemodialysis access procedures. Methods Preoperative vein mapping was conducted in a cross-sectional, observational study in end-stage renal disease patients from August 2005 to May 2010. “Traditional” anatomic description with basilic-brachial junction at the axillary level with paired brachial veins was classified as “Type 1.” Junctions observed at the mid or lower portions of the upper arm with duplication of the brachial vein above that level were classified as “Type 2.” Junctions at the mid and lower portions of the upper arm with no duplication of the brachial vein above that level were classified as “Type 3.” Results Two hundred ninety patients (mean age, 56 ± 17 years; 52% men) were observed and 426 arms mapped (221 right, 205 left). The prevalence of variations in venous arm anatomy was as follows: Type 1: 66%; Type 2: 17%; and Type 3: 17%. Conclusions This study underscores the need for heightened awareness of upper arm venous variations and advocates the regular use of preoperative ultrasound imaging. We propose that recognition of Type 3 anatomy may have implications in access algorithm and planning.