AbstractIntroduction: PHASE is a software for haplotype reconstruction and recombination rate estimation from population data and implements the methods for estimating haplotypes from population genotype data. This software require enormous computing power due to the complexity algorithms used. Recent advancement in grid computing and multi-core processing technology has resulted in the creating of virtual supercomputers (that are capable of massive parallel computations). Method: PHASE version 2.0 was downloaded from PHASE’s homepage (http://stephenslab.uchicago.edu/software.html), and installed on 10 Apple iMac computers (20 CPUs) running Mac OS 10.5 using Apple™ Xserve as a controller. A PHP web-based application was developed to enable easy job submission and result retrieval. Haplotype estimation jobs for PHASE were submitted using a web browser running either from Windows®, Linux® or Macintosh™ OS 10.5 operating systems. Jobs consisting of 20 input files of genomic loci (SNPs) were submitted to the Xgrid via the controller and the job completion time for each run were recorded and compared. Results: The job completion time for estimating 20 input files and returning the results to the controller using XGrid (20 CPUs) took 4,980 seconds compared with 58,800 seconds using a single computer (2 CPUs), representing 91.5% reduction in computing time.