Objective: To describe the implementation and utilization of the Xpert ® MTB/RIF (Xpert) assay to diagnose tuberculosis (TB) among people living with the human immunodeficiency virus/acquired immune-deficiency syndrome (HIV/AIDS, PLHA) in Cambodia. Design: Following the rollout of Xpert, an evaluation was conducted in four provinces of Cambodia from March to December 2012 to determine the utilization, performance, and turnaround time (TAT) of Xpert among PLHA. Data were collected from paper-based patient registers. Results: Of 497 PLHA with a positive TB symptom screen, 357 (72%) were tested with smear microscopy, and 250 (50%) with Xpert; 25 (10%) PLHA tested with Xpert were positive for TB and none were rifampicin-resistant. The utilization of Xpert increased from 23% to 75%, with a median TAT of 1 day. Across districts, utilization ranged from zero to 85%, while the TAT ranged from zero to 22 days. Conclusion: While early data show increasing utilization of Xpert for PLHA with a positive symptom screen, most patients underwent smear microscopy as an initial diagnostic test. Training delays and challenges associated with specimen referral may have contributed to variability in Xpert uptake and TAT, particularly for sites without onsite Xpert testing. Enhanced programmatic support, particularly for specimen referral and results reporting, may facilitate appropriate utilization.