Although fire is regarded as a natural factor in the environment of southern Africa, accidental fires in arid and semi-arid areas influence the fodder flow planning in both agricultural and conservation areas. The short-term impact (two years) of an unplanned fire on the productivity of semi-arid grassland was therefore investigated. Compared to a control treatment not subjected to burning, fire reduced the basal plant cover by 40% after four months and by 18% after two years. Although burnt grassland takes at least two full growing seasons to recover in terms of above- and belowground phytomass production, the belowground growth is more sensitive to fire than the aboveground production. During the first season after the fire, the control area produced nearly double the quantity of phytomass produced by the burnt area. Fire reduced root weight significantly over the first 100 mm of soil depth. More than 80% of the root weight was found in the top 300 mm soil. Accidental fires contribute towards man-made droughts and therefore affect the short-term sustainability of the grassland ecosystem.