Freedom of movement and the opportunity to express normal behaviours are important requirements for any housing system which satisfies the welfare codes (MAFF, 1983). Intensive pig production systems generally house farrowing sows in crates to minimise the probability that piglets will be crushed. To satisfy the welfare codes there is, therefore, a need to develop a loose housing system which satisfies a multiplicity of conditions. It must give the sow unrestrained movement, allow nest building activities, provide physical protection and warm environmental conditions for the young piglets. In a previous choice trial sows sited their nests within cubicles rather than a corner or beside a straight wall (Hunt and Petchey, 1989). In another trial they were offered an arrangement of parallel walls spaced 0.55,0.95 or 1.35 m apart, most sows (0.44) chose to farrow between the 0.55 m spaced walls (Petchey, 1991). Sows making this choice (ie 0.55 m spacing) also exhibited more nest building behaviours and built significantly bigger nests (P<0.05). The trial reported here offers sows the preferred sites of the two previous trials.