Abstract. Many parallel sorting algorithms of (external) disk data have been reported such as NOWsort, SPsort, and hill sort, etc. They all reduce the execution time compared to some known sequential sort; however, they differ in terms of the speed, throughput, and cost-effectiveness. Mostly they deal with data that are uniformly distributed in their value range. If we divide and redistribute data to processors using the fixed and equal division of the key range, all processors will have about equal number of keys to sort and store. But if irregularly distributed data are given, the performance will suffer severely since the partitioning would no longer produce balanced load among processors. Few research results have been yet reported for parallel external sort of data with arbitrary distribution. In this paper, we develop two distribution-insensitive scalable parallel external sorting algorithms that use sampling technique and histogram counts to achieve even distribution of data, which eventually contribute to achieve superb performance. Experimental results on a cluster of 16 Linux workstations show up to three-fold enhancement of the performance compared to previous NOW-sort for sorting 16GB integer keys.