Evaluation studies on active microprocessor-controlled knees (AMPK) in individuals with unilateral transfemoral amputation (TFA) are lacking in the literature. Furthermore, research on user accommodation to AMPK remains to be investigated. Hence, this study aims to conduct a comparison between an AMPK and individual's current prosthesis and assess the accommodation to using an AMPK during daily activities over a 5-week period on functional performance tests.Participants with TFA completed a protocol comprising L-test, slope walking, level walking (2MWT) and dual-task level walking (dual-2MWT) once a week with their current prosthesis and the AMPK. The outcomes of interest were the distance covered during the 2MWT and dual-2MWT, time required to perform the L-test, accuracy of the serial subtractions during the dual-2MWT, heart rate (HR), rating of perceived exertion, fatigue, comfort and perceived workload. Generalised least-squared models were built to investigate differences in prosthetic conditions over time. Pearson correlations were calculated to determine associations between the performance and subjective outcomes. The level of significance was set at 0.05.Seven participants (age = 53 years ± 14 years) completed the study. Over time, the AMPK participants took longer to complete the L-test than their current prosthesis (p < 0.001). They reported higher fatigue (p = 0.033), lower comfort (p = 0.010), and higher perceived exertion with the AMPK (p = 0.048). Slope walking showed no significant walking speed or HR differences except higher HR with the AMPK in session 3 (p = 0.032). Dual-task level walking demonstrated lower walking speed with the AMPK (p = 0.035) and more responses to serial subtractions in sessions two (p = 0.043) and four (p = 0.023). No other differences between conditions were found on one of the functional tests. Weak associations (|r|= 0-0.5) were observed between performance and subjective measures.Using the AMPK highlights initial challenges in task completion times and subjective comfort and fatigue levels. Our findings indicate that five one-hour sessions are insufficient for achieving user accommodation, and underscore the need for further research with a larger sample, continued prosthetic use and user accommodation to enhance prosthetic functioning and user experiences.NCT05407545.