Nematode parasitic bacteria Pasteuria penetrans has been studied for its biocontrol potential against root–knot nematode Meloidogyne incognita. Two isolates of P. penetrans viz., Assam isolate (AM) and Delhi isolate (DL) was taken for this purpose. Study on the spore encumbrance of P. penetrans on root–knot J2 revealed that AM isolate of P. penetrans is more effective than DL isolate. Significantly higher numbers of encumbered J2 and higher numbers of spores per J2 (second stage juvenile) was recorded in the highest level of P. penetrans inoculums in both the isolates. Management of root–knot population by Pasteuria  isolates showed that, both the isolates were effective in reducing nematode population in tomato roots, thereby improving the plant growth parameters in accordance with the increase in inoculum levels. Likewise, number of galls, egg masses and nematode population also declined with corresponding increase in inoculum levels of Pasteuria. Assam isolate (AM) performed better then Delhi isolate (DL) in managing root–knot nematode in Assam agroclimatic condition.