Data on birth weight of 2365 Mecheri lambs born between 1978 and 2005 recorded at Mecheri Sheep Research Station. Pottaneri, Tami Nadu were analysed to identify the factors affecting birth weight of Mecheri lambs. The lambing occurred throughout the year. however majority ofthe Mecheri sheep (7642 per cent) lambed between September and February months. The overall least-squares means for birth weight of males and females pooled over parity and type ofbirth were 2.30 1 0.02 and 2.18 1 0.02 kg respectively. Study on non-genetic factors revealed that the birth weight was highly signiﬁcantly (P<0.0l) affected by period ofbirth. season ofbirth, sex ofthe lamb and parity. Hence, efforts should be made for better management of pregnant ewes when the climatic conditions are not conducive to them.