The present study aimed to investigate the impact of hypothyroidism on left ventricular systolic function using real-time three-dimensional speckle tracking imaging (RT3D-STI). Thirty hypothyroidism patients and forty healthy volunteers were recruited and received RT3DSTI measurement of global longitudinal strain (GLS), global circumferential strain (GCS), global radial strain (GRS), and global area strain (GAS). A comparison of differences between the hypothyroidism patients and those in the healthy group was carried out and we obtained the results as followings. The values of GLS were (-18.93 +/- 3.89) vs. (-21.44 +/- 1.99), with P < 0.01, GRS were (51.13 +/- 11.95) vs. (56.10 +/- 5.76), with P < 0.0; and GAS were (-31.63 +/- 5.38) vs. (-34.40 +/- 2.32), with P < 0.01, i.e. they were lower in hypothyroidism group than those in the health group. While GCS were (-17.75 +/- 1.92) vs. 17.03 +/- 3.45), with P > 0.05, which were not significantly different between the two groups. In linear regres sion, GLS showed significant correlation with both TSH (b = -0.69, P < 0.01) and FT3 (b = 0.71, P < 0.01). Meanwhile, the GRS (b = 2.98, P < 0.05) and GAS (b = 3.11, P < 0.05) linearly correlated with FT3 level. In conclusion, the present study shows that the global longitudinal and radial moves of left ventricular are weaker in patients with hypothyroidism than healthy controls. And the impairment of left ventricular function would aggravate as FSH rises or FT3 declines.