Thirteen Newcastle disease virus (NDV) isolates were characterised based on mean death time (MDT) and intracerebral pathogenicity index (ICPI). Twelve NDV islates were obtained from outbreaks among chickens of various age groups in different parts of Tamil Nadu. Ten NDV isolates were velogenic and three were mesogenic based on both MDT and ICPI. One isolate was placed under group D based on binding pattern with monoclonal antibodies (mAbs). The local challenge virus was found to be velogenic and placed under group C, based on reactions, with mAbs.