Among the four micronutrient cations, deficiency of Zn was found to be widespread in old alluvial soils of Bihar [India]. Available Zn, Cu, Fe and Mn were significantly and negatively correlated with pH and positively with organic carbon. Available Zn and Cu showed a significant negative correlation with soil salinity, and positive correlation with available P2O5. The multiple regression equations revealed that 43, 24, 25 and 24% variations in available Zn, Cu, Fe and Mn, respectively were accounted for by the combined effect of pH, EC, organic carbon and available P2O5 contents. The stepwise regression analysis indicates that the availability of Zn and Cu is dominantly controlled by organic carbon whereas Fe and Mn by pH, organic carbon and available P2O5 content of these soils.