Intravenous (IV) drug using patients often have damaged veins due to injection, making peripheral IV access difficult to obtain. We investigate the relationship between hand dominance and the presence of upper extremity (UE) veins in IV drug (IVD) using patients. We predicted that injection into the non-dominant UE vein would occur more frequently and the dominant UE would have relatively fewer damaged veins. Prospective convenience sample of adult patients with self-reported history of IVD use. Patients excluded for instability, UE amputations, or inability to consent or tolerate a tourniquet. Using a high frequency linear transducer, the volar aspect of each UE was examined in 3 areas to a depth of 2.2cm: anticubital crease, forearm, and proximal arm. Vein patency was assessed by compression. The number of fully compressible veins ≥ 1.8 mm in diameter was recorded. Descriptive information, history of IVD use, and hand dominance was then obtained. The study was powered to detect a vein difference of -2. 19 patients were enrolled; average age was 53.4; 84% were male; 89% were right handed. Patients had an average of 14.6 years of IVD use (range 3-36) with an average of 20.9 years (range 0-276 months) since their last use. 90% of patients had a history of injecting heroin, 76% cocaine, 16% methamphetamine, with 68% reporting the use of more than one substance. 84% reported at least daily use while they were active. 79% stated they injected themselves 100% of the time; the other 4 patients had another person inject for them 20, 10, 5, and 1% of the time. Patients used their dominant hand to inject their non-dominant UE an average of 54% (range 0-100) of the time. The mean vein difference between the numbers of veins in the dominant versus the non-dominant UE was -1.5789. At a 0.05 significance level, there was insufficient evidence to suggest the number of compressible veins between patients’ dominant and non-dominant arms is significantly different (p=0.0872). There is significant variability in injection patterns among IVD using patients. The number of compressible veins visualized with ultrasound was not greater in the dominant UE as expected.