OBJECTIVES We sought to determine the effect of age and sex on procedural outcomes and efficiency of chronic total occlusion (CTO) percutaneous coronary intervention (PCI). METHODS We examined the clinical and angiographic characteristics and outcomes of 1675 CTO-PCIs performed in 1644 patients between 2012 and 2016 at 15 United States centers. RESULTS Mean age was 65.3 ± 10 years and 1408 (86%) were men. Overall technical and procedural success rates were 88% and 87%, respectively. Increasing age was associated with more comorbidities (dyslipidemia, hypertension, prior coronary artery bypass graft surgery, prior stroke, peripheral arterial disease, and chronic lung disease) and more lesion calcification. As compared with the reference age of <65 years, age >75 years was independently associated with technical failure (odds ratio [OR], 2.28; 95% confidence interval [CI], 1.20-4.28). Increasing age was also independently associated with the incidence of major adverse cardiovascular events (MACEs; OR, 2.93; 95% CI, 1.10-9.23 for 65-75 years and OR, 5.71; 95% CI, 1.89-19.60 for >75 years). Compared with men, women (n = 236; 14%) were older (66.8 ± 11.1 years vs 65.0 ± 9.8 years; P=.02), but had similar clinical characteristics and lower J-CTO scores (2.3 ± 1.3 vs 2.5 ± 1.2; P=.02). Although crude technical success rate was higher in women compared with men (92% vs 87%; P=.04), multivariable analysis did not show independent association between sex and technical failure (OR, men/women, 1.66; 95% CI, 0.86-3.50) or MACE (OR, 0.61; 95% CI, 0.25-1.73). CONCLUSIONS Older age, but not sex, is associated with lower technical success and higher in-hospital complication rate for CTO-PCI. CTO-PCI is relatively infrequently attempted in women, despite high technical success and acceptable complication rates.