In this paper, a novel parasitic element structure is proposed to reduce the mutual coupling produced in a compact (2×1) Multi-Input Multi-Output (MIMO) antenna system working at 2.4GHz for Wireless Local Area Network (WLAN) applications. The proposed structure has a rectangular shape with (10) square slots built using FR-4 substrate with relative permittivity of 4.4 and loss tangent 0.025. The resulted MIMO antenna is found to have a low mutual coupling of about -25dB and an envelope correlation coefficient less than 0.1 in the band of interest. The antenna also has a wide relative bandwidth of 18.75%, high total efficiency of 89.5% and acceptable realized gain of about 2.25dBi.