PKS 2155–304 was repeatedly observed in 1979 and 1980 with the International Ultraviolet Explorer. Variations up to a factor of 2 in one year and by 20% in a day are found. The maximum amplitude of variation in X-rays is similar but the timescales are much shorter (a factor of 2 in one day; Urry and Mushotzky, 1982). In all cases the 1200–3100 A continuum is well fitted by a power law with frequency spectral index αUV between −0.7±0.03 and −0.9±0.03. Optical and ultraviolet observations taken within one day show different spectral slopes (Fig. 1). Separate power law fits in the two bands yield αopt = −0.46±0.01 and αUV = −0.80±0.02. The observations by Urry and Mushotzky indicate that the energy distribution steepens further in the soft X-ray region.