A very compact Multiple-Input-Multiple-Output (MIMO) radiator providing dual notches is presented in this paper. It comprises circular ring monopoles fed by a microstrip line embedded with a slot of inverted U-shape. By etching a crescent slot, a split ring resonator slot, a circular slot in the circular monopole, a reversed U-shaped slot inserted along the feeding line, two notches are attained. It operates from 3.5 GHz to 12 GHz that overcomes interference from the Wireless Local Area Network (WLAN) (5.15-5.85 GHz) and X-band (7-8.1 GHz). MIMO antenna has a very compacted dimension of 44 mm × 44 mm × 1.6 mm at the lowest operating frequency and hence is suitable for portable devices. It has dimensions of 0.51λ × 0.51λ × 0.018λ where λ is the wavelength of the lowest operating frequency 3.5 GHz.