Preoperative assessment of calcifications is important in order to choose the correct surgical approach for mitral valve disease. To test the accuracy of echocardiography (ECHO) in the semiquantitative analysis of mitral valve (MV) calcifications we preoperatively echo-studied 66 patients, who were to undergo MV replacement of rheumatic disease. Echocardiograms were performed using a standardized method, recorded on videotape and analyzed by two independent observers. Areas of calcification were identified as dense conglomerate echoes which were brighter than those of adjacent internal structures. After removal, the MVs were evaluated by means of inspection (I), direct radiography (X-ray) and quantitative calcium extraction--EDTA spectrophotometry--(QCa). In the three methods ECHO, I and X-ray, MV calcifications were graded as absent (group 1), mild (group 2) nodular (group 3) and diffuse (group 4). Using the chi square test, no significant differences were found between the three methods, or between ECHO and X-ray, or between ECHO and I, while I grading was slightly lower than X-ray grading (P less than 0.002). Using variance analysis, no significant differences were found in QCa in the three methods within group 1 and 4, whereas significant differences were present within group 2 (P less than 0.002) and group 3 (P less than 0.001), due to the lower sensitivity of I. On the base of the observed distribution of QCa in the removed MVs, the following QCa values: a) less than 20 mg, b) 20-80 mg, c) greater than 80 mg, were considered as the selection criteria for a) absent or mild, b) nodular and c) diffuse calcifications respectively.(ABSTRACT TRUNCATED AT 250 WORDS)