Thirteen thousand eight hundred of Algerian Rumbi ewes were examined, in our study, for lamb's perinatal losses. These ewes belong to fifty breedings of different size, which were distributed on the totality of Tiaret area. These ewes were followed over years 2004 and 2005. The average rate of lamb losses recorded over these two years was 25.09 %; This rate is distributed according to the age of mortality in the following way: 2.90 % of losses were recorded during the last month of gestation 191 Assiut Vet. Med. J. Vol. 52 No. 109 April 2006 (abortions), 9.05 % of stillbirths losses and 13.13 % losses from birth to the tenth day lamb's life. Bad controlled breeding methods, in our sheep herds, were the main factors at the origin of the majority of lamb losses. Among repeated causes, we found abortions, dystocia, crushing of new born, problems of breast feeding and infectious diseases such as respiratory affections and diarrheas.