The origin and migration of oils from selected oil fields in the Gifhorn Trough, NW-Germany was investigated by geochemical analysis of crude oils and possible Lower and Middle Jurassic source rocks. Productive reservoir sandstones in the Gifhorn Trough occur in the Dogger beta zone of the Middle Jurassic (Bajocian), and are interbedded with shales that contain 1–2% TOC mostly Type III kerogen. In the Lower Jurassic (Toarcian) organic matter-rich shales (9–12% TOC) whose kerogen has a type II composition form the best quality oil-prone source rocks. Biomarker and stable isotope analyses of oils and source rock extracts reveal that all oils analysed are derived from the Lower Toarcian shales (Lias epsilon). The timing of oil generation and migration was investigated by reconstructing the geothermal history of the source rock in specific drainage areas and determining the availability of migration pathways through geological time. Hydrocarbon generation started in the central part of the Gifhorn Trough in Upper Cretaceous time. Differences in the maturity of the oils display separate small drainage areas close to the reservoirs. Variations in oil composition within deep buried reservoirs indicate the preservation of different migration phases.