Two field trails were conducted at Sakha Agric. Res.. Station in the two seasons of 2012 and 2013 to study the effect of cyanobacteria (mixture strains of Anabaena oryzae and nostoc muscorum), humic substance (HS) and mineral nitrogen (urea 46.5%N) on yield of some rice varieties (Sakha 101 and Sakha 105).                 It could be observed from the results that the variety Sakha 101 was superior to Sakha 105 in both growing seasons in regard to grain yield and harvest index.                 Results indicated that inoculation with cyanobacteria, application of humic substances and nitrogen fertilization individually significantly increased grain and straw yields, the yield components as well as chlorophyll content and N uptake in plant over their values with the untreated plants in both growing seasons.     Also, the obtained results indicated that the application of 50% cyanobacteria + 50% HS + 50% N fertilizer of the recommended dose in the 1^st and 2^nd seasons achieved the highest values of grain yield (3.89 and 3.68 ton/fed, respectively) ,straw yield (6.57 and 5.66 ton/fed, respectively) ,total chlorophyll (40.14 and 41.6 mg/kg, respectively) ,number of tillers (30.0 and 30.88/plant, respectively),plant height (103 and 101 cm, respectively) and panicle length (26.1 and 24.8 cm ,respectively). While the lowest values of these parameters were obtained with the untreated plants in both growing seasons.                 The interaction between rice cultivars and biofertilizer and nitrogen application was found to be not significant.