Episodic mitral regurgitation due to ischaemia of one or both papillary muscles was studied in a review of 39 cases with complementary investigations and compared with previously reported data. The condition occurred after myocardial infarction in 69 p. 100 of cases (usually after inferior infarction: 54 p. 100) associated with ischaemia of the controlateral territory; there was no history of myocardial infarction in 31 p. 100 of cases. The patients were usually elderly (73 years), often hypertensive (77 p. 100) and diabetic (62 p. 100). The clinical syndrome was that of severe anginal pain, mitral regurgitation and left ventricular failure which was critical in some cases. The ECG showed typical ST depression (4.1 +/- 1.6 mm) especially in the antero-lateral leads; left bundle branch block (28 p. 100) with left axis deviation (18 p. 100), sometimes associated with changes of chronic infarction (64 p. 100) was also recorded. Mitral regurgitation and left ventricular failure regressed almost completely in typical cases between attacks, whilst the ECG showed slight residual sub-endocardial ischaemia (ST depression of 1.5 +/- 0.4 mm) in 30 cases and/or subepicardial ischaemia observed in the anterolateral leads in 13 cases. Phonomechanographic recordings (n = 32) showed moderate mitral regurgitation (1-2/6), usually parasystolic (47 p. 100) or early and mid systolic (36 p. 100) in 87.5 p. 100 of cases between attacks, aggravated by handgrip exercise and improved by trinitrin administration. Echocardiography (n = 27) only showed mitral valve changes in 2 patients (increased density of the papillary muscle in 1 case and prolapse of the anterior leaflet in 1 case); however, segmental wall hypokinetic (51 p. 100) or dyskinetic (15 p. 100) motion, was common with increased left ventricular end diastolic dimensions (mean 56.3 +/- 8.0 mm) and decreased fractional shortening (mean 0.30 +/- 0.07) (67 p. 100). Left atrial dimensions were increased (mean 39.7 +/- 6.4 mm) in 52 p. 100 of patients. Thallium 201 myocardial scintigraphy (n = 32) showed hypofixation in 57 (36 p. 100) and a lacuna in 23 (14 p. 100) of the 160 segments analysed. Left ventricular angioscintigraphy (n = 27; 135 segments) showed hypokinesia in 72 segments (53 p. 100); 2.7 segments per patient), akinesia in 19 segments (15 p. 100; 0.7 segment per patient) and dyskinesia in 2 segments (1.5 p. 100); 0.1 segment per patient). The global ejection fraction was 46 +/- 13 p. 100. Coronary angiography (n = 8) showed significant diffuse atherosclerosis.(ABSTRACT TRUNCATED AT 400 WORDS)