Patterns of daily activity and the factors affecting it were studied in an invading Mediterranean population of American mink, Neovison vison, radiotracked in the northeast of Spain during the post breeding season (winter — half year). We distinguished between local activity, defined as active behaviour without spatial displacement, locomotion activity as active locomotion behaviour while foraging or travelling, and inactivity. We studied the effect of sex, age, daylight (nocturnal or diurnal), month, river flow and average rainfall on the activity of eight males and three females. Male mink presented more locomotion activity than females and subadult mink had more locomotion activity than adult mink. Average rainfall per day had a negative effect on locomotion, while daylight had no effect on either total activity or locomotion activity. Studied mink spent most of their time inactive in-den. These results are accordance with the patterns of activity shown by other native and invasive populations.