introduction: Several reports suggest significantly reduced left ventricular performance in subjects with chronic hypocalcemia. We prospectively investigated eight patients, aged 13 to 31 years, with long-standing hypocalcemia due to idiopathic hypoparathyroidism or pseudohypoparathyroidism by echocardiography. patients and methods: Six subjects had symptomatic hypocalcemia manifested as recurrent tetany (four), seizures (four), mental retardation (three), behavior disorder (one), and skeletal abnormalities (four); three subjects were untreated when studied. None had carciovascular symptoms. Each patient underwent clinical, biochemical, and cardiac studies, including Doppler, two-dimensional, and M-mode echocardiography, on the same day. results: In serum, both total and ionized calcium concentrations were reduced and averaged 7.2 mg/dl (range: 5.3 to 8.5 mg/dl; normal: 9.0 to 10.3 mg/dl) and 3.6 mg/dl (range: 3.0 to 3.9 mg/dl; normal: 4.5 to 5.3 mg/dl), respectively. Electrocardiograms revealed prolonged QTc intervals in six patients. Also noted were prominent U waves (five), T-wave abnormalities (four), and right-axis deviation (one). Resting echocardiography, however, demonstrated normal left ventricular function in all subjects. All M-mode measurements were normal. Two-dimen-sional-derived left ventricular end-diastolic and end-systolic volumes were 87.1 ± 20.1 ml and 30.2 ± 9.7 ml (mean ± SD), respectively. Left ventricular ejection fraction was 65 percent (61.2 to 74.7 percent). Doppler-derived cardiac output and cardiac index averaged 5.1 liters/minutes (2.9 to 6.7 liters/minute) and 3.0 liters/minute/m2 (1.7 to 4.3 liters/minute/,2), respectively. conclusion: Our prospective study of eight subjects with functional hypoparathyroidism demonstrated that, despite electrocardiographic abnormalities, long-standing hypocalcemia was not associated with left ventricular dysfunction.