A novel compact multiband diversity antenna system appropriate for integration onto space-limited devices is presented. It comprises three pairs of printed fractal Minkowski and Koch monopole antennas which resonate in the 1.67–2, 2.3–2.56 and 4.55–5.55 GHz bands, respectively, supporting thus a large variety of wireless technologies for mobile and wireless local area networks (WLANs) applications. The operational characteristics of the antenna system were extracted by simulation using a method-of-moment- (MoM-) based electromagnetic field solver. The diversity performance in a uniform multipath environment under the maximal-ratio combining (MRC) scheme is also evaluated for the two extreme modes of operation, that is, when all three antenna pairs operate simultaneously (worst case) and when only one pair is active while the others being open-circuited (best case). The calculated effective diversity gain (EDG) for the worst/best case is 5.8/6.4, 5.8/7.2 and 7.1/7.5 dB for the 1.8, 2.4 and 5.2 GHz frequencies, respectively.