Vaccine was prepared by using the isolate, exposed to 430C for 12 days. The vaccination was performed in two thousand four hundred breeder flocks (Banoraja) in 3 different flocks @106.5 EID50 per bird oronasally at the age of day 5 (primary vaccination) followed by vaccination through drinking water on day 26 (boostering) in farm condition and thereafter every 45 days interval. The vaccine was also inoculated intranasally @106.5 EID50 in Two thousand backyard birds (Haringhata Black and non-descriptive) and were boostered after 21 days of 1st vaccination with the same dose and subsequent vaccination was performed at every 45 days interval. Serum samples were collected for HI titre at regular intervals and it was observed that the mean antibody both in backyard birds and breeder flocks was above 1.50 ± 00. Therefore, it was concluded that the thermostable live attenuated lentogenic strain Newcastle Disease vaccine after inoculation into backyard birds and breeder flocks, provides satisfactory level of immunity.