This study attempted to assess the effectiveness of the warehouse management system and its users' performance in selected nuclear energy companies in Abu Dhabi, United Arab Emirates. The respondents covered three (3) Nuclear Energy companies for privacy named in this study as X, Y, and Z, with a total of 1,000 population with a sample size of 146 respondents aged 30 to 55. Its effectiveness was assessed through the theory of Just-In-Time Production and its relationship to Human Resource Management and its impact on user performance. A descriptive method was utilized. To analyze and interpret the data, frequency distribution, mean, and independent sample t-tests were employed as statistical tools with a .05 significant level. The findings revealed that most respondents were bachelor's degree holders, officers, and 4 – 6 years in the company. Regarding the performance of duties, the warehousing processes were performed through the W.M.S. implementation. Furthermore, the process improvement, inventory management practices, and productivity and utilization capacity were influential in the W.M.S. implementation. Results also show no significant difference between the respondents' self-assessment performance and the respondents' assessment of W.M.S.'s effectiveness when grouped according to profile.