Objectives: We employed the Illumina NGS platform to sequence genomes of 4 different strains of Pythium insidiosum, an oomycete that causes a serious infection, called pythiosis, in humans and animals. These strains were isolated from humans in Thailand (n=3) and the United States (n=1), and phylogenetically classified into clade-I, -II, and -III. Our study augmented the completeness of the P. insidiosum genome database for exploration of the biology, evolution, and pathogenesis of the pathogen. Data description: Each gDNA sample from the P. insidiosum strains ATCC20026 (clade-I), Pi19 (clade-II), MCC18 (clade-II), and SIMI4763 (clade-III) was processed to prepare one paired-end library (180-bp insert) for whole-genome sequencing by Illumina HiSeq2000/HiSeq2500 NGS platform. A range of 28.4-59.4 million raw reads, accounted for 3.0-7.3 Gb, were obtained and assembled into the genome sizes of 47.1 Mb (15,153 contigs; 85% completeness; 19,329 open reading frames [ORFs]) for strain ATCC20026, 35.4 Mb (14,576 contigs; 83% completeness; 13,895 ORFs) for strain Pi19, 34.5 Mb (11,084 contigs; 84% completeness; 13,249 ORFs) for strain MCC18, and 47.1 Mb (15,162 contigs; 85% completeness; 19,340 ORFs) for strain SIMI4763. The genome data can be downloaded from the NCBI/DDBJ databases under the accessions BCFN00000000.1 (ATCC20026), BCFS00000000.1 (Pi19), BCFT00000000.1 (MCC18), and BCFU00000000.1 (SIMI4763).