Automatic milking systems currently being developed require methods of ensuring that cows adopt postures which allow the attachment of teatcups with one or more robot arms. The ideal posture is for the cow to stand still with its hind legs apart and clear of the udder. Accessibility of the teats was measured by observing whether the rear teats were visible in front of the rear legs from a point 2 m from the side of the cow in line with the rump, 500 mm above the floor. It is desirable that the cow's legs do not obstruct the access path of the robot; an asymmetric stance may ensure that this is the case. Two experiments are described on the effects of passive methods of controlling cow posture. An asymmetric ramped floor had no significant effect on the positioning of the rear feet as a ramp on the left side did not cause the left foot to be placed further back or forward than the right foot. A step on which the cows placed their front feet was effective in improving posture. Steps of 200 mm, 150 mm and 100 mm caused the rear teats to be clear of the rear legs in 93%, 89% and 75% of cases with late lactation cows. There is a significant trend ( P<0.05) associating higher visibility with a higher step. Trough height had no significant effect on the visibility of the rear teats.