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 horticu-ltural fruit set (HFS) values were found in October (May flowering), while the lowest HFS values were found in  September (April flowering) in both cvs during both seasons. IFS and HFS values were significantly higher in Sunset cv compared to Solo cv. Fruit number per tree was higher in Sunset cv compared to Solo cv. On the other hand, yield per tree was higher in Solo cv compared to Sunset cv. The highest fruiting contributed was found in May flowering, whereas the least contribution was found in December     (July flowering) in both cvs during both seasons. Fruit weight, size and pulp weight (%) were significantly higher in Solo cv compared to Sunset cv. October fruiting (May flowering) had the highest values in fruit weight and size, compared to other fruiting dates. TSS, TSS/acid ratio, total sugars and reducing sugars were significantly higher in Sunset cv. The lowest TSS, TSS/acid ratio, total sugars and reducing sugars were found in September (April flowering) compared to those of other fruiting dates.  Ascorbic acid and crude protein content were statistically higher in Solo cv compared to Sunset cv.