An oily Calcium Hydroxide suspension (OCHS) has beendocumented clinically and histologically to enhance the bone regeneration inclosed bone defects and to stimulate the periodontal regeneration inintrabony defects. So far, there are no controlled clinical studies tocompare the effect of the OCHS with the effect of other "biological agents"in treating deep intrabony defects. Aim of the study was to compare thetreatment of deep intrabony defects with an OCHS (Osteoinductal®,Osteoinductal GmbH, München, Germany) to an enamel matrix protein derivative(EMD; Emdogain®, Straumann AG, Waldenburg, Switzerland). Thirty healthypatients, each of whom displayed one intrabony defect, were randomly treatedeither with the OCHS (test) or with EMD (control). Soft tissue measurementswere made at baseline and 6 months following the therapy. No differences inany of the investigated parameters were observed were observed at baselinebetween the two groups. No adverse healing response was observed in any ofthe patients. At six months after the therapy, the sites treated with OCHSshowed a reduction in probing pocket depth (PPD) from 8.60 ± 2.06 mm to 3.27± 1.39 mm and a change in clinical attachment level (CAL) from 10.20 ± 2.08mm to 5.80 ± 2.37 mm (p Palabras clave: oily calcium hydroxide suspension, enamel matrix proteins, periodontal regeneration