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Petrographic study of selected thin sections from the Aptian dolomites in the Razzak Oil Field, Egypt reveals three dolomite textures. These textures have been classified based on crystal size, shape, uniformity, and trace element distribution. These textures are as follows: 1) finely crystalline, planar-e dolomite, 2) medium to coarsely crystalline, non-planar dolomite, and 3) very coarsely crystalline, non-planar dolomite (saddle dolomite). Stable isotope analyses indicates that the Aptian dolomites formed in a marine environment and were later subjected to several diagenetic modifications that affected the original sediments. The finely crystalline, planar-e dolomite is penecontemporaneous in origin with delta O-18 that ranges from -7.51 to -8.14 parts per thousand VPDB and delta C-13 that ranges from +0.39 to -1.27 parts per thousand VPDB. The medium to coarsely crystalline, non-planar dolomite is a replacement type with a meteoric origin. In this non-planar dolomite, the delta O-18 ranges from -7.99 to -8.82 parts per thousand VPDB and the delta C-13 ranges from -0.58 to -1.35 parts per thousand VPDB. The void-filling (saddle dolomite) is the product of chemical compaction and is associated with the thermal sulfate reduction event. This saddle dolomite has delta O-18 that ranges from -7.89 to -8.76 parts per thousand VPDB and delta C-13 that ranges front +1.41 to +2.42 parts per thousand VPDB. The diagenetic parasequence of the Aptian Dolomite is recorded by: 1) deposition of the original sediments (lime mud); 2) dolomitization; 3) silicification, 4) pyritization, and 5) precipitation of saddle dolomites (pore-filling dolomite).