An electro-hydraulic seismic simulator (EHSS) is a testing equipment whose main purpose is to reproduce reference seismic accelerations on test structures. This paper presents the application of LQR-based control to improve acceleration and displacement tracking and repeatability performance of a uniaxial EHSS. The structure of the proposed controller is composed of a command generator, a displacement feedback system, and a state observer. Four LQRbased feedback systems are investigated: linear quadratic regulator (LQR), linear quadratic integral (LQI) control, linear quadratic tracking (LQT) control, and a variation of LQT named here LQTβ. The dynamic model of the EHSS is obtained using differential equations based on hydraulic theory and physical laws, and its parameters are estimated using gray-box model identification. The proposed controllers are implemented in the uniaxial EHST at Universidad Industrial de Santander, where their performance is evaluated in terms of acceleration and displacement tracking and repeatability, and the results are compared against a conventional PID control. Experimental results showed superior performance of LQR-based controllers over PID, achieving the best results with LQR and LQTβ.