To assess the influence of chamber design and depth on the accuracy and precision of sperm measurements, manual counting of a standardized latex bead solution and automated sperm motility measurements were made using a Makler chamber (Sefi Medical Industries, Haifa, Israel), Neubauer hemocytometer (American Optical Company, Buffalo, NY), and a new, disposable device (Micro-Cell; Cyto Fluidics, Inc., Silver Spring, MD). Bead counts obtained with the Micro-Cell chamber or hemocytometer were not statistically different from those determined by electronic particle counting, whereas Makler chamber counts were 62% higher. Makler counts had a significantly higher standard deviation, suggesting that counts made with this device are less reproducible. Analyzing live sperm samples, the percentage of motile sperm determined using Micro-Cell and Makler chambers were similar. However, significant differences in sperm concentration and mean velocity were found. The Micro-Cell disposable chamber provided consistent and accurate data on sperm concentration, percent motility, and mean velocity. These differences in sperm measurements emphasize the importance of sampling chamber characteristics on data reliability.