AIMS: The accurate postoperative assessment of mitral valve repair is important not only to document operative outcome, but also to confirm the functional morphology of the repaired valve. METHODS AND RESULTS: We assessed 25 consecutive patients following mitral valve repair with transthoracic real-time 3-dimensional echocardiography (RT3DE) and 2-dimensional echocardiography (2DE). We compared the adequacy of the visualization of the mitral valve Carpentier segments, the site of the repair, and the accuracy of planimetry by RT3DE and 2DE in estimating the postoperative mitral valve area (MVA), compared to the Doppler-derived pressure half-time (PHT) value. Inter-observer variability and feasibility were also assessed for RT3DE. Adequate visualization of the mitral valve segments was more frequently obtained by 3DE imaging (163/170 by 3DE vs. 121/170 by 2DE, P < 0.001). In particular, the mitral valve commissures were more clearly identified with 3DE. 3DE also was significantly better at correctly identifying the site of the repaired segment (26/30 by 3DE vs. 19/30 by 2DE, P < 0.05). The difference in MVA (mean difference +/- SD) determined by 3DE planimetry, when compared to PHT was -0.21 +/- 0.46 cm(2) and -0.44 +/- 0.95 cm(2) for 2DE (P = 0.014). Planimetry by 3DE more closely correlated with the MVA calculated by PHT than 2DE planimetry (r = 0.89 for 3DE vs. r = 0.6 for 2DE). Imaging with RT3DE was both feasible, with a mean acquisition time of 4.02 +/- 1.68 min, and data analysis time of 15.82 +/- 3.9 min, and reproducible, with good inter-observer variability for segment scoring with 3DE (kappa = 0.79) and mean inter-observer difference in assessing MVA by 3DE planimetry of 0.18 +/- 0.12 cm(2) (P = NS). CONCLUSION: This study suggests that RT3DE offers additional morphological postoperative data of repaired mitral valves, and increases the accuracy of MVA estimation by planimetry. It is both feasible in a busy echocardiography department and reproducible.