The assessment of mitral valve anatomy can be difficult or even misleading on standard cardiac imaging procedures. Such is the scenario in a 40-year-old woman with an incidental finding of atrial septal defect (ASD) and consideration of a trileaflet versus double-orifice mitral valve (DOMV) on transthoracic two-dimensional echocardiography. Further interrogation using transesophageal two dimensional and transthoracic three-dimensional (3D) echocardiography (to allow more accurate assessment and simultaneous viewing of multiple imaging planes) revealed the typical “seagull wing” configuration of the mitral valve on long-axis view and two distinct but nearly equal-sized orifices on short-axis view, one oriented anteriorly and the other posteriorly. The patient’s DOMV was classified as an incomplete bridge type as confirmed on 3D imaging, with each orifice having its own set of papillary muscles and chordal attachments. The mitral regurgitation was graded as severe, resulting from leaflet prolapse of the anterior orifice. No left ventricular outflow tract obstruction was demonstrated in this case, and the overall left ventricular systolic function was preserved. The ASD was of the primum type, with the configuration and exact location verified through 3D imaging. The accurate detection of congenital anomalies via noninvasive techniques and complementary advanced modalities is vital for preoperative planning, as well as anticipation of potential complications related to the structural anomalies. To our knowledge, this is the first local report of DOMV with primum ASD in an adult.