Objectives: To investigate a strategy for ultra-low volume contrast percutaneous coronary intervention (PCI) with the aims of preserving renal function and observing the 90-day clinical endpoint in patients with non-ST-elevated myocardial infarction (non-STEMI) and chronic kidney disease (CKD).Background: The feasibility, safety, and clinical utility of PCI with ultra-low radiocontrast medium in patients with non-STEMI and CKD are unknown.Methods: A total of 29 patients with non-STEMI and CKD (estimated glomerular filtration rate [eGFR] of ≤60 ml/min/1.73 m 2 ) were included. Ultra-low volume contrast PCI was performed after minimal contrast coronary angiography using zero contrast optical coherence tomography (OCT) guidance. Pre-and post-PCI angiographic measurements were performed using quantitative flow ratio (QFR) for preperfusion assessment and verifying improvement.Results: The median creatinine level was 2.1 (inter-quartile range 1.8-3.3), and mean eGFR was 48 ± 8 ml/min/1.73 m 2 pre-PCI. During the PCI procedure, OCT revealed 15 (52%) cases of abnormalities post-dilation. There was no significant change in the creatinine level and eGFR in the short-or long-term, and no major adverse events were observed. Conclusion:In non-STEMI patients with high-risk CKD who require revascularization, QFR and no contrast OCT-guided ultra-low contrast PCI may be performed safely without major adverse events. K E Y W O R D S chronic kidney disease, contrast-induced nephropathy, optical coherence tomography, percutaneous coronary intervention, poststent abnormalities, quantitative flow ratio 1 | INTRODUCTION Contrast-induced nephropathy (CIN) and poststent abnormalities are associated with increased short-and-long term morbidity and Zheng-Yu Liu and Zi-hui Yin contributed equally to this study and should be considered as co-first authors.