Objective: One and a half repair strategy (i.e. adjunct bidirectional cavopulmonary shunt in addition to an intra-cardiac repair) can be employed for patients with small and / or dysfunctional right ventricle (RV). The efficacy and safety of this procedure in adult population, however, needs to be defined. Methods: A retrospective review of 12 patients with various congenital anomalies, who underwent one and a half repair between December 2001 and May 2008, was performed. Median age at operation was 45.9 years (17.3 – 57.5 years). There were 7 males and 5 females. Diagnoses were Ebstein���s anomaly in 10, giant right atrium (RA) with hypoplastic RV in 1 and tricuspid stenosis associated with Behcet���s disease in 1. Procedures for intra-cardiac anomalies were tricuspid valve repair using Hetzer technique for Ebstein���s anomaly in 9, tricuspid valve replacement for Ebstein���s anomaly with previous tricuspid valvuloplasty in 1, RA reduction plasty for giant RA in 1 and tricuspid valve replacement for tricuspid stenosis in 1. Postoperative functional magnetic resonance study was undertaken in 7 of them. Results: There was no early or late mortality. Median ventilatory support, intensive care unit stay and hospital stay were 13.5 hours, 2 days and 10 days, respectively. Postoperative central venous pressure at postoperative 24 hours ranged from 12 to 28 mmHg (median: 16 mmHg). Three patients (3/12, 25%) showed signs of central venous hypertension necessitating diuretics administration. Median follow-up was 25.3 months (2.5 – 78.2 months). Postoperative functional MR study was performed in seven patients at 9 to 69 months postoperatively. Blood flow to the upper compartment of the body was 19-36% (median: 0.28) of the whole body blood flow, and the ratio of superior vena cava blood flow over blood flow to the upper compartment was 0.45 – 1.0 (median: 0.8). Conclusion: One and a half repair can be performed safely in adult patients with marginal right ventricular size and function. Postoperative functional MR study showed that the efficacy of one and a half repair varies according to the anatomical disposition of each patient.