Background: Of the three common central access sites, subclavian vein catheterization has the lowest risk of infection but the highest risk of pneumothorax. The main disadvantage of the short-axis ultrasound guided approach is difficult needle-tip visualization. We describe use of the hydrolocation technique to improve needle-tip localization.Case: Two females, an 81-year-old and a 72-year-old, presented for coronary artery bypass grafting requiring central vein cannulation. To confirm that the needle tip was visualized and not the shaft, needle advancement was paused and 1 ml of saline injected. The appearance of a small anechoic pocket superficial to the subclavian vein helped to visualize the needle tip. Negative aspiration was then re-applied and slight advancement resulted in aspiration of blood and successful subclavian vein puncture. Conclusions The use of hydrolocation for subclavian vein access was easily implemented, required little modification in setup and technique, and provided improved localization of the needle tip.