The article considers the basic factors of the industry, which influence the internal financial control system in an oil company. The basic functions of internal financial control in an oil company are identified. Three main inherent features of the industry in respect of internal control are studied in the article: correlation between the company size and financial leverage ratio, correlation between product originality and raised loans, and, finally, negative asset tangibility ratio. Additionally, the importance of a seasonality factor while building up an internal control system is highlighted by the author. As a result, the key functions of internal control in an oil company are summarized.