A field experiment was conducted during the winter seasons of 1999-2000 and 2000-2001 at Varanasi, Uttar Pradesh, to evaluate the effect of varying row ratio, lndian mustard [Brassica juncea (L.) Zernj. & Cosson] variety and fertility levels on yield potential, competitive function and economics of wheat + lndian mustard intercrop- ping. Association of wheat with lndian mustard under 5 :1 row ratio was found more sustainable, as it accounted for higher value in terms of land-equivalent ratio (LER) and relative crowding coefficient (1.690) and was eco- nomically more remunerative. For association with wheat, lndian mustard var. 'Sanjucta Asesh' proved economi- cally viable than 'Vardan' with a minimum depression in yield and yield attributes of wheat. To achieve higher yield advantage and efficient resource utilization, an application of 100% recommended dose of fertilizer to both the component crops was found imperative. Though performance of wheat was better in its sole stand, lndian mustard varieties thrived better in intercropping treatments to their solid stands. Key words : + mustard intercropping, Row ratio, Mustard variety, Fertility, LER, Economics, Rela- Wheat tive crowding coefficient