A field experiment was conducted under All India Coordinated Research Programme on Weed Control at Crop Research Centre of Rajendra Agricultural University, Bihar, Pusa, Samastipur during rabi season of 2004-05 and 2005-06 in calcareous sandy loam soil with an aim to evaluate the effect of different density of Phalaris minor on growth and yield of wheat. Higher density of Phalaris minor retrogressively affected plant height, spike length, crop biomass and grain yield of wheat. The level of reduction in wheat yield was 12 to 66% corresponding to an increase in density of Phalaris minor from 25 to 150/m2. The present data showed the need for adoption of suitable weed management practices in wheat field with the density of Phalaris minor at 25/m2 and above.