The objective of this study was to evaluate the yield response of potato to inoculation with Bacillus sp. OSU-142 at three levels of N fertilization (0, 120, and 240 kg ha-1) under field conditions in Ahlat District of Eastern Anatolia Region of Turkey in 2006 and 2007. Tuber inoculation with Bacillus sp. OSU-142 significantly affected yield and yield components in both years. Tuber yields and yield components were higher at all levels of nitrogen fertilizer in the inoculated plots as compared to the control. However, beneficial effect of Bacillus sp. OSU-142 on tuber yield was noted at 120 kg N ha-1, possibly indicating either more effective of inoculation in the low-N input agriculture or an interaction of Bacillus sp.OSU-142 with higher yielding seasonal conditions. In general, more response to inoculation was observed in the absence of major crop growth limitations, suggesting the complementary contribution of the Bacillus sp.OSU-142 treatment to more efficiently developing higher yielding potato. © 2009 Academic Journals.