Shale oils produced from Eastern and Western oil shales by the Fischer assay and IGT hytort processes have been investigated by both H and C high resolution NMR techniques, as were hydrotreated Eastern shale oils obtained by the IGT Hytort process. From the NMR data of the shale oils, the average molecular structure parameters were calculated as well as mole percents of aromatics, olefins and alkanes. Although it is recognized that the parameters have little exact meaning, the values do represent quantitatively the compositional differences observed in the NMR spectra of the shale oils resulting from the two retorting processes. Differences in chemical composition are discussed for the Eastern and Western shale oils. Also discussed are the solid state carbon-13 NMR spectra of Eastern and Western oil shales before and after retorting by the Fischer assay and IGT Hytort processes.