The aim of our study was to assess the welfare of pregnant sows housed in collective pens, based on indicators such as behavior, skin lesions and lameness in two commercial farms where the floor area (A- continuous, B- slatted) and environmental enrichment have been different. Observations were made on 120 pregnant sows (LandracexLarge White), during pregnancy period. Behavior was assessed by direct observation, and each event was expressed in terms of total active behavioural manifestation. Skin lesions were rated on a three degree scale from 0 to 2 (absence of lesions, surface lesions, severe lesions). Investigation behavior was clearly shown in B pens (67%) compared with A (52%) in the first and last weeks of gestation; a high incidence of positive social interactions was recorded in A pens (21%). Number of sows with lameness was higher in A pens (3,9%) compared with B pens (1,7%), and the skin lesions of 4,5% in B pens. All indicators monitored have recorded changes in both pen types. The welfare of pregnant sows should be evaluated using different criteria depending on breeding technology.