Abstract: Nigeria is rich in water resources in the South but relatively poor in the North. Increasing watershed degradation and decreasing water quality, among other factors have posed serious management challenges. Integrated Water Resources Management (IWRM) is seen as a promising approach to ensuring the sustainable management of Nigeria�s water resources. Despite the acceptance of IWRM, the extent of its implementation at the river basin level in Nigeria is poorly understood. This paper uses a secondary data analysis to obtain a better understanding of the extent of IWRM implementation at the river basin level in Nigeria. Findings show that IWRM implementation in Nigeria is limited and constrained by the regulative forces. To improve implementation, the paper suggests the need for institutional reforms in which IWRM elements are adequately embedded in relevant legal and regulatory frameworks in Nigeria.