The objective of the study was to analyse periparturient behaviour and the reproductive parameters of native Puławska sows with regard to polymorphism (insertion/deletion) at the PRL locus as components in the assessment of maternal value. The analysis included 45 sows of known genotype at the PRL locus, which were managed under a conservation breeding programme in individual farms. Behaviour was assessed by using an ethogram of sow responses to the stockpersons and piglets during the rearing period. The production parameters included litter size between days 1 and 21, mortality, body weight and daily weight gains of the piglets during that period. The performed analyses and observations show an association between the polymorphism of PRL gene and the maternal parameters of Puławska sows. Del/Del homozygous sows exhibited significantly higher realised fertility, but the maternal characteristics were generally more favourable in sows of the PRL Ins/Ins genotype. These animals were more docile towards the stockpersons and piglets, and were characterised by lower crushing rates, generally lower litter mortality, and higher parameters of piglet growth and development.