Objective: To determine the adherence by laboratories across the United States to the standard semen analysis guidelines and parameter reference ranges 10 years after being set by the World Health Organization (WHO) in 1999 and to compare compliance between regional laboratories vs. specialty assisted reproductive technology (ART) laboratories. Design: Observational study. Setting: Regional clinical and reproductive endocrinology andrology laboratories. Intervention(s): Blank or deidentified semen analysis reports were collected from laboratories through direct contact or from reports received as part of clinical care for male infertility. Main Outcome Measure(s): Adherence to semen analysis reference range reporting as recommended by the 1999 WHO guidelines. Result(s): Semen analyses reports were collected from 111 laboratories from 31 different states. Of 111 laboratories, 26 (23%) reported all reference range parameters in accordance with the guidelines. Of 65 ART laboratories, 21 (32%) complied with all reference range parameters as outlined by the guidelines, vs. 5 of 46 non-ART laboratories (11%). Seventy percent of laboratories that did not report 1999 WHO parameters did so because of differences in reference values for normal morphology. Conclusion(s): Adherence to WHO 1999 semen analysis reference range guidelines has not been achieved by ART and non-ART laboratories 10 years after being introduced. Non-ART laboratories report reference ranges less accurately than ART laboratories. © 2011 by American Society for Reproductive Medicine.