More stringent requirements for PDO (protected designation of origin) cheese products and societal demands are encouraging farmers to promote grazing and favour biodiversity. Trials were conducted for two years in an upland region to compare animal performance, grass productivity and biodiversity in two dairy grazing systems: DIV–, managed with rotational grazing on former temporary grassland at a ‘high’ stocking rate (1.8 LU ha-1); and DIV+, managed with continuous grazing on diversified permanent grassland at a ‘low’ stocking rate (1.0 LU ha-1). Twelve cows per system were compared, with no concentrate supplementation. At the beginning of the grazing season, DIV+ showed higher milk production than DIV– (+ 2.1 kg d-1 per cow), due to a greater herbage allowance and better quality of grass selected by cows. Two months later an inversion of the milk production curves was observed, following the fall in grass nutritional value. From July to September, DIV– allowed a similar milk production to that of DIV+ in 2008, and a higher production in 2009 (+ 1.5 kg d-1 per cow). Animals’ weight was not affected by the systems. Insect and flora biodiversity was greater in DIV+. This study supports that the two upland dairy systems have both advantages and limitations in the context of PDO cheese production.