The aim of this study was i) to assess the effects of stress in pregnant ewes on the subsequent behavioural reactivity of lambs, ii) to find out if these effects are modulated by the temperament of the ewes (active vs. passive), and iii) to determine if an enrichment of the rearing conditions after weaning could alleviate the consequences of prenatal stress. The results show that lambs born from stressed ewes were more reactive than those of control ewes. The effect of stress varied according to the temperament of the ewes: lambs born from active ewes were more affected than those from passive dams. The lambs that were reared under the enriched conditions after weaning were less frightened by a human or an unknown object than those living in standard rearing conditions, but this effect was more pronounced in lambs from control ewes. Therefore stress during pregnancy alters the behavioural reactivity of lambs especially since the dam has an active temperament. Nevertheless, such alterations induced by prenatal stress can be minimized by the enrichment of post-weaning housing conditions.