Aims: Using intravascular ultrasound (IVUS), we sought to characterize coronary morphology in women with chest pain without major epicardial obstructive coronary artery disease (CAD). We have previously observed an unexpectedly high rate of adverse outcomes among women with chest pain and normal or insignificant obstructive CAD. Information about the presence and characteristics of coronary atherosclerosis in these women could provide insight into the mechanisms related to increased risk, as well as improved diagnosis, prevention, and treatment. Methods: Women (n = 100) with suspected ischemia without obstructive CAD (>50% stenosis) underwent IVUS of a left coronary segment with measurements by a core lab masked to clinical and angiographic findings. Results: Angiograhic core lab analysis found 69.6% of patients had no (a<20%) and 30.4% had minimal (20-<50%) CAD. IVUS segmental images were interpretable by the core lab in 92 women, with 19 (21%) having no atherosclerosis (intimal-medial thickness <0.5 mm). In the remaining 73 women (79%), percent atheroma volume was 27 A;circ;± 8% and mean maximum plaque thickness was 0.53 ± 0.22 mm. Thirty-eight women with atherosclerosis (53%) had >30% of interrogated vessel involved. The average vessel involvement was 40%, and the maximum plaque thickness was 1.27 mm. The number of risk factors strongly correlated with percent atheroma volume (r = 0.53, P < 0.0001) and percent vessel involvement (r = 0.51, P < 0.0001), with the strongest independent predictor of both being age. Remodeling was assessed in 59/73 women (81%), and 73% had evidence of positive remodeling. Conclusions: In symptomatic women without significant luminal obstructive CAD, we observed a high prevalence of atherosclerosis with positive remodeling and preserved lumen size. These findings may help explain increased risk and emphasize need for improved diagnostic and treatment options for women with concealed CAD.