The availability of urban green space (UGS) is one of the environmental factors that is frequently linked to increased levels of physical activity (PA). Positive associations with increased levels of PA are reported for the amount of UGS close to home, the distance to the nearest UGS, the size of the nearest UGS, and the presence of certain features. However, the evidence to date is somewhat inconclusive, and dominated by studies from North America and Australia. There is a large variation in city structures, and recommendations for North American or Australian cities are not automatically valid for European cities. Using a sample of 1305 Danish adults and detailed descriptions of UGS, we examined the association between UGS and outdoor PA in general, as well as PA in the nearest UGS. No association between outdoor PA in general, size of, distance to, and number of features in the nearest UGS was found. The amount and number of UGS within 1. km revealed no association either. For PA in the nearest UGS positive associations with size, walking/cycling routes, wooded areas, water features, lights, pleasant views, bike rack, and parking lot were found. This indicates that PA in a UGS might be stimulated by providing these features there. However, interventions or longitudinal studies are needed to explore potential causal relationship.