Abstract: A review of the development of oil refining is made from the construction of the first process units. Three periods in the development are outlined. During the first period till 1960, small-scale units were constructed with out-of-date equipment and technologies, which were used for processing of insignificant quantities of crude oil. During the 2nd period (60’s and 70’s of the past century) the refinery complexes in Burgas and Pleven were constructed employing large-scale capacities for crude oil processing with modern equipment and technologies. However, crude oil was processed by a simple topping-reformer method leading to the utilisation of the light fuel potential. During the 3rd period deeper processing of crude oil was employed that resulted in a significant yield of light fuel and improved quality of crude oil derivatives. The development of technologies and methods of crude oil refining is outlined. The dynamics of the throughput of the units, quantities of crude oil processed and the main products are shown. An estimation of the degree of utilisation and efficiency of crude oil is provided. The strategic importance and the contribution of this industrial sector for the development of the economy of Bulgaria and covering the domestic demand for crude oil derivatives and petrochemicals is illustrated. The conclusion made is that the crude oil refining and petrochemical industries have a priority development in this country with the existing capacities running on a maximum throughput aiming at rapid economical growth and increased standard of life.