OBJECTIVES: Chronic kidney disease (CKD) and end-stage kidney disease are well-established risk factors for early mortality and morbididy in patients with coronary artery disease.  However, there is limited data on the subsequent hospitalizatons and related direct healthcare costs among patients with pre-existing CKD undergoing percutaneous coronary intervention (PCI).  We aimed to compare the rates and costs of cardiac-related hospital readmissions following PCI in patients with and without pre-existing CKD.  METHODS:  Direct healthcare costs were estimated from 12,998 patients enrolled in the Melbourne Interventional Group (MIG) registry, who underwent PCI between April 2004 and October 2010.   Only individuals with data on cardiovascular-related hospitalizations and medication use at 12-month follow-up were included.  Individual patient-procedures were assigned unit costs based on published (DRG) data from the National Hospital Cost Data Collection for Admissions in Victoria, Australia (2008-2009) and the Australian Pharmaceutical Benefit Scheme schedule (2011-2012).  A ‘bottom-up’ costing approach was used. Costs relating to the index procedure and in-hospital complications were excluded. Bootstrap linear regression was used to estimate the association between direct medical costs and CKD categories, adjusting for age, gender and relevant comorbidities.  RESULTS:  Excess cardiac-related readmissions occurred among patients with estimated glomerular filtration rate (eGFR) <30 ml/min/1.73m2 (“severe CKD or dialysis”, N=330; 35%), compared to eGFR: 30-60 ml/min/1.73m2 (“moderate CKD”, N=2,648; 28%) or patients with eGFR≥60 ml/min/1.73m2(“referent group”, N=10,020; 24%).  Adjusted mean (95%CI) total follow-up costs were significantly higher in patients with severe CKD or dialysis [$AUD 2,206 ($AUD 1,148 - 3,688)]. CONCLUSIONS: Patients with severe CKD/dialysis undergoing PCI procedures incurred the highest mean direct healthcare costs at 12-month follow-up, compared to those with better renal function.  Hospitalization accounted for the majority of these expenditures. Data gathered from this study have the potential to inform policy makers of the likely economic impact of CKD in the context of invasive treatment of CAD.