Abstract. The aim of the present study was to investigate whether oxytalan fibers are formed in the regenerated human periodontal ligament. 6 patients, each of them exhibiting an advanced intrabony defect, were treated with a bioresorbable membrane according to the GTR‐principle. Following a healing period of 6 months, the teeth were extracted together with their surrounding soft and hard tissues and subsequently fixed in 10% buffered formalin. Following decalcification in EDTA, the specimens were embedded in paraffin and 8‐μm histological sections were cut in the mesio‐distal direction, parallel to the long axes of the teeth. The sections were stained with hematoxylin and eosin, or with the oxone‐aldehyde‐fuchsin‐Halmi staining method and examined in the light microscope. A regenerated periodontal ligament containing newly‐formed oxytalan fibers was observed in all specimens. Many of them inserted into the newly formed cementumon the root surface. It is concluded that oxytalan fibers are formed de novo in human regenerated periodontal ligament tissue.