This data set contains two ASCII files (.txt format). One file provides monthly above-ground live biomass, dead matter, and litter data and daily above-ground net primary productivity (ANPP) data for a temperate grassland steppe at the Media Luna Ranch in Patagonia, Argentina (45.60 S 71.42 W Elevation 630 m) for the period May 1981 to March 1983. The second file contains climate data recorded at ... Media Luna Ranch from 1981 through 1985. Productivity of the steppe was monitored at monthly or bi-monthly intervals during two growing seasons. The ANPP measurement presented here is the sum of the increase in above-ground live biomass, dead matter, and litter. ANPP was estimated to be 0.00-0.15 g/m2/day in winter months (May-September) and 0.22-0.94 g/m2/day in the warmer months. Annual ANNP was estimated to be 35 g/m2/year. The study site is a 2.5 hectare exclosure situated on the Rio Mayo terraces. The steepe represents one of the most important grassland areas of Patagonia which occupy a narrow belt in the foothills of the Andes. The region has been over-grazed by introduced livestock since the early 1900s, and is currently used for sheep production.