Objective: Our aim was to study the effect of primary hyperparathyroidism (PHPT) and parathyroidectomy (PTX) on left ventricular (LV) wall thicknesses and systolic and diastolic function. Methods: Fifteen patients with untreated PHPT were evaluated by applying Doppler and digitized M-mode echocardiography before and 2–3 months after PTX. Fifteen age- and sex-matched healthy controls were also examined echocardiographically. Results: Prior to PTX, interventricular septal thickness (IVST), LV mass (LVM), aortic root dimension and left atrium dimension were greater and LV fractional shortening was slightly decreased in patients as compared to controls. Significantly increased LV peak late diastolic velocity (A<sub>max</sub>) and isovolumic relaxation time, and a slightly decreased ratio of peak early to peak late diastolic velocities (E/A<sub>max</sub>) in the patients indicated impairment of LV diastolic function in hyperparathyroidism. PTX reduced serum total Ca from 2.79 ± 0.13 to 2.39 ± 0.09 mmol/l (p < 0.001) and tended to reduce IVST [10.6 ± 2.1 vs. 10.4 ± 2.0 mm; not significant (n.s.)], LV posterior wall thickness (9.6 ± 2.0 vs. 9.2 ± 1.0 mm, n.s.) and LVM (250 ± 102 vs. 213 ± 42 g; n.s.). Before PTX, there was a significant correlation between serum total Ca and LVM (r = 0.63, p < 0.05), and the PTX-induced change in serum total calcium correlated with the change in LVM (r = 0.59, p < 0.05). PTX induced no significant changes in LV systolic or diastolic function during the follow-up of 2–3 months. Conclusions: The present findings indicate that PHPT induces LV hypertrophy, slight impairment of LV systolic function and significant impairment of LV diastolic function, which are not substantially improved after TX and 2–3 months of normocalcemia.