In mild climatic regions, open camp systems (dry lots) may be used for dairy cattle. These have a lower capital investment cost than intensive housing systems although the management of open camps is more difficult. The effect of (a) an earthen mound within an open camp and (b) different camp sizes on the production performance, some physiological parameters and behaviour of Dutch-type Friesian cows were determined over two winter seasons. The feed intake of cows in the earthen mound camp was higher (P < 0.05) than that of cows in the smaller camp. Production and physiological parameters of cows, however, did not differ (P > 0.05) between camps with and without an earthen mound. Similarly production and physiological parameters of cows in camps of different sizes (100 vs 200 m2/cow) did not differ (P > 0.05). The ground surface of the large camp was drier than that of the small camp resulting in cleaner cows (P < 0.01) while the washing time of udders at milking was shorter (P < 0.01). Cows in the small camp stood for longer periods (P < 0.01) to avoid lying down in wet areas. Cows in the large camp spent more time (P < 0.01) lying down. Although no difference in production para¬meters was observed in both trials, an earthen mound and camps of at least 100 m2/cow may be necessary in high rainfall areas.