The structure and related production are described in five oil and gas fields of the eastern coal field of Kentucky, namely (1) the Lee-Estill-Powell oil field, (2) the Campton oil field, (3) the Owsley County gas field, (4) the Clay County gas field, and (5) the Elliott County oil field. The producing beds are Pennsylvanian, Mississippian, Devonian, and Silurian in age, the next important being the Corniferous limestone of the Devonian. The major structural features of the general area are the Cincinnati Arch and Paint Creek uplift, whose axes extend north and south, and the Pine Mountain and the Irvine-Paint Creek faults and uplifts, whose axes extend east and west. These two systems of folding are dominant features in eastern Kentucky. The Cincinnati Arch has had a mar ed effect on both structure and stratigraphy. It was probably a positive element throughout the time of deposition of the formations in these fields. Formations increase in thickness with distance from the arch, and minor folds parallel the arch. Subsequent folding and faulting with east and west axes were the result of pressure from the south. Production is related to structure only in a general way; the porosity of the sands and limestones seems to be the controlling factor for oil and gas accumulation. Several wells have been drilled in the Elliott County oil field proving the crest of the main fold to be dry, probably because of unfavorable sand conditions. An interesting feature of the map of the eastern coal field is the relation of the oil and gas production and the isocarbs to th major uplifts and faults. The Irvine sand pools, which produce 60 per cent of the oil in the state, lie along the flank of the Irvine-Paint Creek uplift, paralleling the Irvine-Paint Creek fault. The Wier pools, which produce 30 per cent of the state's oil, lie along the axis of the Paint Creek uplift. This close relation of production to uplift bears out the theory that oil was formed during, and as a result of, folding, rather than having been formed prior to the fold and having subsequently migrated into it. Folding seems essential to oil accumulation in eastern Kentucky, but the degree of folding must not pass beyond a certain point or the hydrocarbons will be changed to gas. The most favorable formations for producing oil are stratigraphically high, geologically young, and moderate y folded. The probability of finding many new oil fields of importance is not large.