BACKGROUND The purpose of this study was to analyze predictive performance of MCV in midterm ischemic events among SCAD patients undergoing elective PCI. MATERIAL AND METHODS We retrospectively included 226 consecutive patients with SCAD who received elective PCI. The patients were grouped based on MCV quartile values. The prognostic significance of MCV was assessed using univariate and multivariate Cox proportional hazard regression analyses. RESULTS According to MCV quartile points (87.5 fL, 89.7 fL, and 92.4 fL, respectively), the included patients were divided into 4 groups, with an average follow-up of 34.2 months. There were 28 (48.3%) patients with stent thrombosis in the 1st quartile, 24 (29.1%) in the 2nd quartile, 18 (31.6%) in the 3rd quartile, and 15 (27.8%) in the 4th quartile (log-rank test, P=0.027). Multivariate analysis confirmed that MCV 1st quartile (HRadj=2.047, 95% CI 1.041-4.026; P=0.038), ALT (HRadj=1.013, 95% CI 1.004-1.023; P=0.004) and number of PCI vessels (HRadj=1.198 95% CI 1.013-1.415; P=0.034) were risk factors for ischemic events. The restenosis rate in patients belonging to the MCV 1st quartile was 2 times higher than that in MCV 2nd, 3rd, and 4th quartile groups (P=0.007). CONCLUSIONS MCV value may be independently correlated with restenosis in SCAD patients undergoing PCI. Low MCV predicts high risk of in-stent restenosis.