Abstract The influence of a single row plantation of Acacia nilotica on the growth and productivity of agricultural crops was assessed in the arid regions of Haryana, India with Triticum aestivum (wheat), Trifolium alexandrinum (barseem), Cicer arietinum (chickpea) and Gossypium hirsutum (cotton) being raised on the southern side of tree belt. Crop density, biomass production (of shoot and root), crop growth (in terms of shoot and root length) and yield of all the four crops increased with increasing distance from the tree canopy. A direct negative correlation (correlation coefficient value 0·9 or above in the majority of characters) between parameters studied and the distance from the tree was noticed. The maximum affect was observed in shoot biomass (reduced by 58, 42, 42, and 41% in T. aestivum, T. alexandrinum, C. arietinum and G. hirsutum, respectively) and minimum affect was on root growth. Yield reduction due to trees up to 15 m distance was 37·8, 49·0, 40·6 and 34·4% in T. aestivum, T. alexandrinum, C. arietinum and G. hirsutum, respectively. It is suggested that farmers holding small parcels of land should not grow crops in association with A. nilotica trees under arid conditions.