Percutaneous balloon-mitral-valvotomy (PBMV) is an alternative to surgery in selected patients with mitral valve (MV) stenosis (MS). Applying echocardiography, suitability for PBMV is assessed by detailed morphological description. Echo-scores alone are suboptimal to describe MV morphology, because single parameters, important for a decision concerning PBMV, are not distinguishable out of a score number. The aim was to design a tool (coding-system), which combines a number for a stenotic MV like scores (for statistical options) and decodable, generally applied parameters describing the MS morphology. The reproducibility of the MS morphology using the coding-system has to be tested in 90 patients. A separate group of 297 patients (pts) with MS, scheduled for PBMV, should be investigated prospectively applying the coding-system and a comparable score. We chose the Wilkins score (WS) as representative of scores. The coding-system is designed as a parameter sequencing set consisting of 6 digits. The first digit indicates a decision code concerning suitability for PBMV. The following 5 digits indicate generally accepted morphological parameters, which are partially also used in the WS. Therefore, the MS morphology can be “read” retrospectively by decoding. 201/297 patients were found suitable for PBMV. Applying the coding-system all 201 suitable patients were correctly distinguished from 96 morphologically unsuitable patients. Astonishingly 48/96 of the rejected patients showed a WS ≤8 whereas 28/201 of the suitable patients demonstrated a WS >8. 25/28 of them showed a successful initial outcome. Applying the generally known threshold of “8” when predicting suitability of a MS, the WS demonstrated an initial success rate of 62 %, sensitivity of 0.87, specificity of 0.45, precision of 0.79, and accuracy of 0.78. Applying the coding-system, the initial success rate was 70.8 %, sensitivity = 0.96, specificity = 1.0, precision = 1.0, and accuracy = 0.97. The coding-system is an advanced diagnostic aid, is statistically applicable, offers a decodable morphological description, includes a decision code regarding suitability for PBMV, and can be used for comparing different groups of patients with MS by calculating “mean morphologies” of groups.