Aim: The purpose of the present study was to compare clinically the treatment of deep intrabony defects with an enamel matrix protein derivative (EMD) to access flap (AF) surgery, in an early evaluation at 6 months after the therapy. Methods: Twenty-five patients suffering from chronic periodontitis, and displaying a total of 32 intrabony defects, were randomly treated either with EMD (test) or with access flap surgery (control). Gingival parameters and soft tissue measurements were made at baseline and at 6 months following therapy. Results: No differences in any of the investigated parameters were observed at baseline between the two groups. Healing was uneventful in all patients. At 6 months after therapy, the test group showed a reduction in mean probing depth (PD) from 7.88±1.67 to 4.00±1.32 mm (pConclusions: Within the limits of the present study, it can be concluded that: (i) at 6 months after surgery both therapies resulted in significant PD reductions and CAL gains, and (ii) early evaluation (at 6 months) of the treatment with EMD resulted in no higher CAL gains and PD reductions than the treatment with access flap surgery. Keywords: enamel matrix proteins, intrabony defects, early evaluation