A metamaterial based isolation enhancement technique is proposed. A 4-shaped MIMO antenna system is used to demonstrate the effect of the a metamaterial based isolation structure between the radiating elements. The isolation structure is capable of enhancing the isolation for the dual band MIMO antenna system under consideration. Printed CLLs on the top layer of the antenna system provides the isolation for high band (2.3-2.98Ghz). The ground layer complementary CLLs are used to enhance the isolation in the low band (827-853MHz). The minimum isolation for the low band and high band was 18.9dB and 9.8dB respectively.