AA7075 and AA7020 alloys were prepared using a vacuum melting furnace and a casting furnace. Microstructural properties of the alloy samples were examined in both as-cast and heat-treated conditions. In order to investigate the effect of heat treatment, various designed AA7075 and AA7020 samples were homogenized in two steps (300 oC/12h+475 oC/12h) and then aged under different regimes. The effects of heat treatment on the microstructures were studied using optical microscopy (OM), scanning electron microscopy (SEM)/energy-dispersive X-ray (EDX) elemental analysis, transmission electron microscopy (TEM), and X-ray diffraction (XRD) analysis. The microstructural properties of both alloy systems (AA7075 and AA7020) were compared both within themselves and with each other, depending on how they were exposed to heat treatment. The analysis of EDX and XRD patterns reveal that the aged AA7075 and AA7020 alloys contain α-Al matrix phase, MgZn2 and Al2CuMg intermetallics, with the MgZn2 IMC phase being the only one detected in the aged AA7020 alloy sample, which is evident from the TEM micrographs showing polyhedral shaped Al2CuMg particles about 30-50 nm in size and spherical shaped MgZn2 particles about 10-30 nm in size dispersed in the eutectic phase and at the grain boundaries.