The effect of microbial inoculants on yield performance of maize based cropping systems under rainfed conditions in Northern Karnataka on a clay loam soil was studied with various treatment combinations including crop- ping systems and seed priming treatments during Kharif 2007. Bio-priming (16.60 μg TPF g soil-1 day-1) and combina- tion of all priming methods (16.10 μg TPF g soil-1 day-1) resulted in significantly higher dehydrogenase activity than farmers practice (13.78 μg TPF g soil-1 day-1). Similar results were obtained in urease and phosphatase activity and also percent root colonization of VAM fungi. Among the different cropping systems followed, sole cropping resulted in higher kernel yield (67.40 q ha-1) and HI (0.433) over intercropping. Among the different priming methods, bio- priming (58.35 q ha-1) and combination of all priming methods (58.85 q ha-1) were found advantageous over farmer's practice (53.09 q ha-1). Similar results were obtained in stover yield of maize.