Hydrocarbon evaluation of the Lower Jurassic age of Kurdistan Region (Northern Iraq) is highly recommended while the middle and upper Jurassic parts were evaluated in most parts of the Region. Liassic source rock evaluation is very helpful in further understanding the regional Petroleum Geology of Kurdistan and Iraq as well. This book comprises study of four different rock units of Liassic (Toarcian) age; which are Adaiyah, Mus, Alan, and Sehkaniyan Formations, in view point of Petroleum geology. It contains analysis, results, and interpretations with conclusions associated with the most valuable knowledge regarding the richness, potential, type, and maturity of hydrocarbon as well as interpretation of depositional environment of organic matter. It also clarifies some troubles regarding Jurassic petroleum system of Kurdistan. This text comprises petrographic study of these rock units and their evaluation regarding reservoir quality, porosity and its types, facies distribution, and depositional environments which supports the main ideas of present oil companies in Kurdistan.