The survival of the yeast mutant rad 54-3, which is temperature-conditional for the repair of double-strand breaks, was measured after exposure to UV-light (254 nm) and incubation at 23 degrees C and 36 degrees C. It was found that survival was drastically reduced with incubation at the restrictive temperature. Temperature-shift experiments indicated that repair of UV-induced damage which is controlled by the rad 54 gene proceeds with a half-value-time of about 7 h.