A polylactide-polyglicolide(PLA-PGL) has been documented clinically to enhance bone regeneration in closed bone defects and to sustain periodontal healing in intrabony defects. So far, there are no controlled clinical studies to compare the effect of the PLA-PGL with the effect of other "biological agents" in treating deep intrabony defects. Aim of the study: to compare treatment of deep intrabony defects with PLA-PGL(Fisiograft®,Ghimas,Italy) to an enamel-matrix-protein-derivative(EMD; Emdogain®,Straumann AG,Waldenburg,Switzerland). Nineteen patients, displaying 26 intrabony defects, were randomly treated with PLA-PGL (test) or with EMD(control). Soft tissue measurements were made at baseline and 6 months after. No differences in the investigated parameters were observed at baseline between groups. Wilcoxon and Mann-Whitney tests were used for statistics. Alpha-error was set 0.05, the power-of-the-study 0.57. No adverse healing response was observed. Six months after, sites treated with PLA-PGL showed reduction in probing pocket depth (PPD) from 7.77±1.48mm to 3.38±0.77mm (p=0.001) and a change in clinical attachment level(CAL) from 9.08±3.57mm to 4.77±1.09mm (n.s.). In the group treated with EMD, PPD was reduced from 7.54±1.20mm to 3.85±1.28mm (p=0.001),CAL changed from 8.15±1.14mm to 5.85±1.28mm (p=0.016). No or little hard tissue fill was observed radiographically in the defects treated with PLA-PGL. Both treatments resulted in improvements of PPD and CAL. A statistically significant difference between the groups in favor of Fisiograft® group was observed with respect to CAL gain(p=0.029),no statistically significant PPD reduction difference between groups in favor of Fisiograft® was observed. At six months, both therapies seemed to lead to significant improvements of the investigated clinical parameters. Schlagwörter: polylactide-polyglycolide, enamel matrix proteins, intrabony periodontal defects