Background: This retrospective study aims to explore whether there is a safe maximum waiting period for completion of TCPC (total cavopulmonary connection) after bidirectional Glenn (BDG) anastomosis. Methods This study incorporates 42 patients, who had 2 or more years follow-up following BDG. Our policy has been to perform TCPC only, when we had arterial oxygen saturation (SaO2) deterioration and/or parental dissatisfaction of their child's health. We assessed SaO2, physical growth, parental assessment of child's health, ventricular function, AV valve regurgitation, and systemic ventricle volume index data immediately after the operation, after 2 years (usual TCPC completion period) and during the last visit Results: The mean follow-up of the 42 patients was 66.2 +/- 30 (24-147) months SaO2, systemic ventricular ejection fraction and systemic ventricle volume index remained unaffected during the follow-up period. There has been improvement of physical growth estimated by weight (p<0.001) and height (p<0.0001) percentiles. 40 (95 %) of the parents assessed their child's overall health as satisfactory and 2 (5 %) as unsatisfactory in early post operational period, and remained 32 (80 %) and 8 (20 %) respectively in last visit. There has been statistically significant increase of AV valve regurgitation by 0.3 grade (p<0.008). Conclusion: If we choose to, it may be safe to wait up to 5 years, before performing completion TCPC following BDG, provided AV valve regurgitation is followed closely.