Damage by radiative frosts is a major limiting factor for coffee cultivation in southern Brazil (south of 20° S latitude). The use of Mimosa scabrella (bracatinga) as a shade tree, to modify the local energy balance and thus prevent damage to the coffee plants, has been evaluated from 1986 to 1994. The study was carried out near Londrina, Parana State (23°23' S, 51°11′ W). During the experimental period, several radiative frosts with intensity ranging from moderate to very severe occurred at the site. Minimum coffee leaf temperatures during these events were 2 to 4 °C higher in the shaded plots. Due to frost protection, coffee bean yields on the average of 7 harvests were higher on the shaded plots. The potential of this system for frost protection in southern Brazil is discussed.