This study analyzed the trends and pattern of institutional credit supply to agriculture during pre- and post-financial reforms along with their determinants. It then compared the effects of reform policies on access to institutional credits in Nigerian agricultural sector before and after the reforms (1978 - 1985; and 1986 -2009). Relying mainly on time series data from CBN and NBS, it used ordinary least squares method (linear, semi-log and double log) to model the determinants of banking sector lending to the agricultural sector during the review period. The models were subjected to several econometric tests before accepting one. Chow test was used to verify the presence of structural change in the selected equation before and after the reforms. Results indicated an exponentially increasing trend of agricultural credit supply in the economy after the reform began. Econometric analysis shows that stock market capitalization, interest rate and immediate past volume of credit guaranteed by ACGSF significantly influenced the quantity of institutional credit supplied to the agricultural sector over the period in review. There was a significant difference between the credit supply function during the pre-reform and post reform periods. It was recommended that government must consider interest rate regulation as a veritable tool for making credit accessible to farmers at affordable levels; increase fund allocation to ACGSF; boost monitoring capacity of CBN on banks generally and strengthen the microfinance banks to be more responsive to agricultural credit needs.