Summary - Isolates of Heterorhabditis were identiŽ ed as H. indica using the following molecular diagnostic features: hybridisation to a H. indica speciŽ c satellite DNA probe; AluI and MboI restriction proŽ les of the rDNA ITS PCR product and the AluI proŽ le of the rDNA IGS PCR product. The Kenyan isolates represent a distinct subgroup of H. indica. These isolates lacked one of the two Hinf I restriction sites which are present in the rDNA ITS product of all the other isolates tested and they also differed from other H. indica isolates in their rDNA IGS HaeIII restriction proŽ le. The Indian isolates are interfertile. The Kenyan isolates are interfertile but only one Kenyan isolate, Ki3, produced viable progeny when crossed with H. indica LN2. The four Indonesian isolates are interfertile, but only one Indonesian isolate (INA H1) produced viable hybrids when crossed with H. indica LN2. INA H1 was also interfertile with the Kenyan isolate Ki3.