The influence of flowering waves on pollen viability, fruit set and fruit quality of Solo and Sunset papaya cultivars under the arid land environment was studied during 1996 and 1997 seasons.Results indicated that under the environmental conditions of Giza, Egypt, papaya trees started to form flower buds from March towards mid-May. Normal flower opening appeared during April till July with a duration average of 40 days from emergence to anthesis.Pollen viability was significantly higher in Sunset cv compared to Solo cv. Pollen viability of April flowering was found to have the lowest value compared to the other flowering waves (May, June and July)The initial fruit set (IFS) of May flowering was the highest in both cvs followed by July flowering and the lowest IFS values were always for April flowering. The highest horticultural fruit set (HFS) values were found in October (May flowering), while the lowest HFS values were found in September (April flowering) in both