Lameness can be assessed using locomotion scoring; however, this method is time consuming and an automated method of detecting lameness is needed. Studies have shown that in conventionally-managed dairy herds, lame cows spend more time lying down than non-lame cows (e.g. Singh et al, 1993). However, there are limited data available for high producing zero-grazed dairy cattle in the UK. IceTags™ are activity monitors which use an electronic accelerometer to determine the percent of time spent standing, lying or active and have been validated in a study by Munksgaard et al (2006). The aim of the present study was to assess the impact of lameness on lying behaviour of high yielding, zero-grazed, Holstein dairy cows and to assess the potential use of lying time to detect lameness.