Acetabular orientation affects the success of total hip arthroplasty. Computer-assisted navigation systems may reduce positional errors. Total hip arthroplasty results were analyzed using an imageless navigation system. We hypothesized that reliability and accuracy would improve. One hundred forty-nine total hip arthroplasties were performed using minimally invasive surgical techniques in 3 cohorts: manual (n = 53), initial navigation cases (n = 49), navigation second series (n = 47). Manual patients' cup orientation variation from desired range was -19 degrees to +18 degrees anteversion (SD, 9.1 degrees ), -11 degrees to +25 degrees abduction (SD, 6.7 degrees ). Navigation variation from desired was -18 degrees to +15 degrees (SD, 7.3 degrees ) in group 1 and -15 degrees to +9 degrees (SD, 5.9 degrees ) in group 2 in anteversion and -15 degrees to +13 degrees (SD, 6.1 degrees ) in group 1 and -15 degrees to +11 degrees (SD, 4.7 degrees ) in group 2 in abduction. Results were statistically significant. There were significant differences for operating room time and estimated blood loss, but not incision size or body mass index. Navigation provided controlled, reproducible acetabular alignment; but a learning curve existed in terms of accuracy, estimated blood loss, and operating room time.