Our objective was to determine the distribution of these virulence genes among C. jejuni isolated from stool of human diarrhea. All isolates belonged to one of 20 known capsule types and all were assayed by PCR for T6SS, a hemolysin co-regulated protein (hcp) gene, and GBS-associated genes (cgtA, cgtB, cstIIHS19 and cstIIHS2) which are involved in sialic acid production in the lipooligosaccharide (LOS) cores of C. jejuni. Results: Of all isolates with these 20 capsule types identified, 328 (62.6%) were pos. for hcp, ranging from 29.2 to 100% among 10 capsule types. The GBS-associated LOS genes were detected among 14 capsule type isolates with 24.4% and 23.3% of C. jejuni isolates possessed either cstIIHS19 or all three genes (cgtA, cgtB and cstIIHS19), which were classified as LOS classes A and B whereas 9.2% of C. jejuni isolates possessing cstIIHS2 were classified as LOS class C. The C. jejuni isolates of LOS A, B, and C together accounted for 56.9% of the isolates among 14 different capsule types while 31.1% of all C. jejuni isolates did not possess any GBS-associated genes. No significant difference was detected from C. jejuni isolates possessing GBS-associated LOS genes among travelers and children, but changes between those with hcp were significant (p < 0.05). Conclusions: Our results suggested a high diversity of hcp and GBS-associated LOS genes among capsule types of C. jejuni isolated from Thailand.