Effects of irrigation, inoculants and fertilizer nitrogen (N) on N₂(C₂H₂) fixation in peanuts were studied in 1976 and 1977 at Delhi, Ontario. Inoculant application increased nodulation and N-fixation in both years. Powdered peat and granular formulations containing the same strains of rhizobia resulted in almost the same amounts of nodulation and N-fixation (80 kg/ha on average). Differences in nodulation from inoculants containing different strains of rhizobia were not consistent over the two years. However, 60% difference in N-fixation resulted from the inoculants containing different strains of rhizobia in both years. Nitrogen application decreased the nodule number, nodule dry weight, and N-fixation of all the inoculated peanuts. Irrigation increased the N-fixation of the peanuts treated with granular inoculant in 1976 by an average of 45% and all the inoculated peanuts in 1977 by an average of 54% but had no effect on nodulation in either year.