For a study, the researchers aimed to evaluate the prevalence of pseudarthrosis following antepsoas (ATP) lumbar and lumbosacral fusions. A total of 220 patients (average age: 66 years, 82 males (37.2%), and 127 (57.7%) smokers) were taken. About 8 patients (3.6%) were determined with pseudarthrosis. Nearly 693 discs were addressed using the ATP approach. Of those, 681 (98.3%) were considered fused (641 levels [92.5%] were “definitely fused,” and 40 levels [5.8%] were “Likely fused”) and 12 discs (1.7%) developed pseudarthrosis (7 levels [1.0%] were “likely not fused,” and 5 levels (0.7%) were “definitely not fused”). The highest rate of pseudarthrosis was found at L5-S1 (4.8%) compared to the L1-L5 discs (0–2%). Of 127 smokers, 6 developed pseudarthrosis (odds ratio=2.3,P=0.3). The fusion rates were 95.3% and 97.8% for smokers and nonsmokers, respectively. Of 8 patients who developed pseudarthrosis, only 4 (50%) were determined to be symptomatic, of whom 2 (25%) required revision surgery. Both of these patients were smokers. The overall revision rate due to pseudarthrosis was 0.9% (2 of 220 patients). The MIS-ATP technique resulted in high fusion rates (96.4% of patients; 98.3% of levels). Pseudarthrosis was noted mostly at the L5-S1 discs and in smokers.