Abstract: The residual effect of a mixture of blue-green algae (Anabaena variabilis, Aulosira fertilissima, Scytonema sp., Calothrix javanica and Westiellopsis prolifica) on the growth and yield of two cultivars of rice (BR-3 and BR-7) grown in two consecutive seasons was studied. Four treatments were considered viz. No- Control, UN- Chemical fertilizer applied 24 hours before transplantation, AN- Algal mixture applied seven days after transplantation and UN+AN- Fertilizer and algal inoculum used together. Results showed positive residual effect in terms of leaf breadth and length, number of grain and yield of straw in t. Aman season. Increase in grain yield over control was recorded in Boro and t. Aman season following only AN treatment. Combined effect of UN+AN was much better over control in first, second and third crop respectively. Highest amount of nitrogen and protein content of rice grain, nitrogen uptake by grain, nitrogen content of plants and uptake of nitrogen by plant were recorded suggesting positive residual effect of algalization. Enhancement effect of nitrogen fixation by blue-green algae on the yield of rice was found to be significant at 5% level.