Increasing behavioural autonomy of animals ensures their adaptation to various environments and contributes to the sustainability of livestock production. More particularly, maternal behaviour is vital for the offspring survival. Breed differences in maternal behaviour are well known but genetic variation within breed has been poorly investigated. The aim of the study was to estimate in sheep genetic parameters for maternal reactivity and search QTL associated with the related behavioural traits. Ewes (n=851) reared outside were individually phenotyped just after lambing in two behavioural tests based on the reactivity to separation from their lambs and/or to a human. Ewes were tested for one or two lambing. In the first test performed outdoor 2 hours after lambing, the ewe’s reactivity was assessed by measuring flight distance from lambs, time to restore contact with lambs and facility to follow transport of lambs. In the second test performed indoor 24 h after lambing, the ewe’s reactivity was assessed by measuring vocalizations, locomotion and proximity to lambs with or without human presence. Lamb mortality was recorded until weaning. Heritability estimates were moderate (h2=0.11 to 0.23±0.05) for flight distance from lambs, time to restore contact with lambs and facility to follow the transport of lambs. Genetic correlations between these traits ranged from 0.78 (±0.21) to 0.95 (±0.06). For the second test, heritability estimates ranged from 0.11 (±0.05) for proximity to 0.50 (±0.05) for vocalizations. Genetic correlations ranged from 0.13 (±0.06) to 0.44 (±0.07). Lamb mortality was significantly lower in ewes showing a higher maternal reactivity. A genome wide association study of maternal reactivity is currently carried on in ewes genotyped using the Illumina ovineSNP50 beadchip. The moderate to high heritabilities and potential SNPs polymorphisms for the behavioural traits of ewes may offer opportunities in genetic selection for improving maternal behaviour and reducing lamb mortality.