High　performance　integrally-finned　tubes　with　external　fin　density　of　54　and　56　fpi　are　designed　and　manufactured.　The　condensing　heat　transfer　of　R134a　on　five　tubes　with　integral-fin　density　of　20,　37,　48,　54,　56　fpi　and　five　different　high　performance　three　dimensional　enhanced　tubes　are　studied　for　their　single　horizontal　tube.　Condensate　inundation　experiment　of　the　integrally-finned　and　three-dimensional　enhanced　tubes　is　also　performed.　The　experimental　results　indicate　that　the　specially-designed　integrally-finned　tubes　No.4　and　No.5　of　high　density　show　the　highest　overall　heat　transfer　performance　over　the　three　dimensional　enhanced　tubes　about　8%.　For　the　lower　fin　density　integrally-finned　tube,　the　results　show　apparently　no　condensate　inundation　influence　effect.　For　the　higher　fin　density　tubes,　the　heat　transfer　is　firstly　enhanced　more　or　less　with　the　condensate　impinging　from　the　above　tube,　then　maintains　nearly　unchanged.　For　the　3-D　enhanced　tubes,　the　heat　transfer　is　also　enhanced　with　condensate　inundation　firstly　except　tube　No.7,　while　it　is　all　followed　by　a　mild　drop　as　the　increase　of　condensate　rate.　As　a　whole,　the　performance　of　the　integral-fin　tube　with　high　density　is　better　than　that　of　the　3-D　enhanced　tubes.　(C)　2012　Elsevier　Ltd.　All　rights　reserved.