['Seasonal differences in step counts have been observed in a limited number of studies conducted on US adults. Due to the diverse global climate, assessment and interpretation of seasonal patterns in ambulatory activity may vary between countries, and regionally specific studies are necessary to understand global patterns. Currently, no studies have assessed whether a seasonal trend is present when ambulatory activity is measured objectively in adults living in the UK.', 'The present study investigated whether pedometer-determined step counts of adults living in the UK vary between summer and winter.', 'Ninety-six adults (52% male, age = 41.0 +/- 12.3 years, BMI = 26.1 +/- 5.1 kg m(-2)) completed a within-subject bi-seasonal pedometer study. All participants completed two 4-week monitoring periods; one during the summer and one the following winter. The same Yamax SW-200 pedometer was worn throughout waking hours during both seasons, and daily step counts were recorded in an activity log. Intra-individual seasonal changes in mean daily steps were analysed using a paired samples t-test.', 'Summer mean daily step counts (10 417 +/- 3055 steps day(-1)) were significantly higher than those reported during the winter (9132 +/- 2841 steps day(-1)) (p < 0.001). A follow-up study conducted the subsequent summer in a sub-sample (n = 28) reinforced this trend. Summer step counts were significantly higher than winter step counts on all days of the week (p < or = 0.001). A significant day of the week effect was present in both seasons, with step counts reported on a Sunday being on average 1500 steps day(-1) lower than those reported Monday through to Saturday.'] Do uK adults exhibit higher step counts in summer compared to winter months?