In this paper, a pair of parasitic parallel coupled line resonators (PCLR) is printed between the two patches that reduce the mutual coupling in multiple-input-multiple-output (MIMO) antenna system. The proposed design offers reduced edge-to-edge spacing of 3.5 mm (0.066λo, λo is the free space wavelength) at 5.7 GHz. The proposed decoupling structure of length 0.49λo and area 0.05λo × 0.49λo consists of a pair of parallel coupled lines, placed between the antenna elements and provides a band stop properties over the desired operating band that helps to eradicate the near coupled field. The PCLR decoupling structure helps to improve the isolation and bandwidth by 16 dB and 0.22 GHz, respectively, at the resonating frequency without any change in radiation characteristics of the MIMO system. Moreover, the antenna system yields a good broadside gain of 6.43 dBi, efficiency 70–85%, with acceptable channel diversity performances over the entire operating band (5.47–5.9 GHz). Good agreements between the simulated and measured results make the proposed design approach suitable for a closely packed MIMO system. © 2019 Wiley Periodicals, Inc.