We present detailed and high-resolution grain size data of the terrigenous matter from the upper 8.30 m of marine sediment core KL42, southern Red Sea. The core was recovered at 15°54.9' N and 41°34.7' E from a water depth of 958 m during RV Sonne cruise SO121 in 1997. After removing carbonate and organic matter, the grain size distribution was measured with a Beckman Coulter LS13320 laser particle analyzer (Beckman Coulter Life Sciences, Indianapolis, IN, USA). Volume percentages are given for 116 grain-size classes between 0.0004 mm and 2.0 mm. Concentrations of clay (<0.002 mm), fine silt (0.002-0.0063 mm), medium silt (0.0063-0.02 mm), coarse silt (0.02-0.063 mm), fine sand (0.063-0.2 mm), medium sand (0.2-0.63 mm), and coarse sand (0.63-2.0 mm) were calculated.