This thesis examined why the prices of petroleum products continues to be priced differently in Nigeria despite the existence of uniform pricing law on petroleum products. The study also examined the principle of deregulation of downstream petroleum sector in Nigeria in order to posit the key argument of how the policy affects economic activities in Nigeria. Arising from this, the study pay attention to the introduction of uniform pricing law from 1973 and the application of subsidy regime as a social welfare scheme to assist consumers have easy access to the product and also enable industries reduce cost of production of goods and services. The introduction of deregulation policy by the Federal Government was to cured the failure of the uniform pricing law in determining prices of petroleum product, however, the policy is faced with growing challenges in supply and distribution of petroleum products that has led to variation in prices of petroleum products all over the country. The research adopted doctrinal and empirical research methodologies by reviewing all principal statutes, subsidiary legislations and analysis of data collected from field survey on aspect of deregulation introduced into the downstream sector in order to resolve the problems of variation in price of petroleum products in the country. All issues relating to the study were carefully analyzed and examined, which culminated into findings and recommendations. From the analyses carried out, the study revealed that there are apparent conflicts between the Petroleum Act and the Petroleum Products Pricing Regulatory Agency Act with respect to price fixing of petroleum products. In the downstream petroleum sector though prices of petroleum products are fixed uniformly throughout the country the later introduction of deregulation policy by the government has caused variation in prices of petroleum products. Findings from this study further revealed that subsidies on petroleum products are only provided in the yearly budget estimates submitted to the National Assembly by the President of the Federal Republic of Nigeria instead of making such provision in the Uniform Price Law. The equalization schemes put in place by government to re-imburse marketers the cost of transporting petroleum products all over the country has not been able to stabilize petroleum products prices at a uniform price because of the inability of government to promptly pay marketers the cost incurred in transporting the products to different locations in the country. The lack of enforcement of the uniform pricing policy as contained in the Uniform Price Law by the various regulatory agencies in the downstream sector has caused scarcity and hoarding of petroleum products, which breeds sharp practices ranging from adulteration and increase in the price of petroleum products. Therefore, it cannot be concluded that prices of petroleum products are regulated only by the government under Section 6(1) of the Petroleum Act but by other variable factors that varies price of petroleum products. The thesis ends up with the recommendations that the National Assembly should harmonize the provisions of Petroleum Act and the Petroleum Products Pricing Regulatory Agency Act relating to price fixing in order to address the problems of variation in the price of petroleum products in the country. The repeal of the Petroleum Equalization Fund Management Board Act is overdue because the operation of equalization schemes is bedeviled by corruption and inefficiency. The Petroleum Products Pricing Regulatory Agency Act is not an efficient legislation that will deregulate prices of petroleum products in the country therefore it calls for more vibrant legislative interventions.