Introduction: It has been reported that a nodular calcification is associated with a calcified nodule and the reappearance of in-stent failure after percutaneous coronary intervention. Hypothesis: This study evaluated characteristics of nodular calcification on optical frequency domain imaging (OFDI) image in comparison to histopathology. Methods: One hundred and seven matched OFDI and histopathological cross-sections from 13 coronary arteries of 5 human autopsy hearts were evaluated. In histopathological assessment, a nodular calcification was defined as a fragmented calcification with accumulated fibrin. In OFDI analysis, calcification arc, shape of luminal surface, lumen side shape of calcification, irregularity of lumen surface, and irregularity of calcification surface of lumen side were analyzed in each OFDI image. Results: There were 10 nodular calcifications and 97 non-nodular calcifications in histopathological slices. The calcification arc was significantly smaller in nodular calcification than in non-nodular calcification [89.5° (56.4-108) vs. 126° (82.0-190), p =0.02]. OFDI features of a nodular calcification were characterized by a convex shape of the luminal surface (90.0% in nodular calcifications vs. 6.2% in non-nodular calcifications, p <0.01), a convex shape of calcification (90.0% vs 18.6%, p <0.01), an irregular luminal surface (50.0% vs 0%, p <0.01), and an irregular calcification surface of lumen side (60.0% vs 3.1%, p <0.01). Conclusion: This study suggests that OFDI has a potential capability to distinguish between nodular calcification and non-nodular calcification based on angle of calcification, shape and irregularity of luminal surface and those of calcification.