We　have　previously　developed　bare　narrow-bore　capillary　chromatography.　In　this　work,　high-performance　DNA　separation　was　realized　for　a　size　range　of　10-800　base　pairs　(bp)　utilizing　bare　narrow-bore　capillary　chromatography　with　750　nm-radius　capillaries.　Separation　behavior　of　double-stranded　DNA　(dsDNA)　fragments　was　investigated　over　a　range　of　eluent　concentrations　and　elution　pressures.　DNA　molecules　were　hydrodynamically　separated　in　a　size-dependent　manner　in　free　solution　without　any　sieving　matrices,　with　the　longer　fragments　being　eluted　out　from　the　capillary　earlier.　It　was　found　that　the　eluent　concentration　variously　influenced　the　transport　behavior　for　different-sized　DNA　fragments　depending　upon　the　configuration　of　DNA　molecules　and　the　association　of　counterions.　Ionic　strength　of　the　solutions　strongly　impacted　DNA　persistence　length.　Enhanced　elution　pressure　could　shorten　analysis　time　with　a　slight　loss　in　resolution.　Excellent　efficiency　of　two　million　theoretical　plates　per　meter　was　achieved,　which　indicates　the　enormous　potential　of　bare　narrow-bore　capillary　chromatography　for　the　analysis　of　DNA　fragments.　These　findings　would　be　useful　in　understanding　the　transport　behavior　of　DNA　fragments　in　confined　dimensions　for　chromatography　in　free　solution.