The purpose of this study was to compare histological effectiveness of platelet pellet (PP), which has higher platelet content than platelet-rich plasma, and the combination of PP/guided tissue regeneration (GTR) for class II furcation defects in dogs. The mandibular second, third, and fourth premolars of both sides in four dogs were used. Class II furcation defects (5 mm in height and 2 mm in depth) were surgically created. Five weeks after the first operation, second premolars were treated with scaling and root planing (group 1); right third and fourth premolars received PP (group 2), and left premolars received the combination of PP/GTR (group 3). Percentage of cementum and alveolar bone formation were evaluated by histometric analysis after a healing period of 12 weeks. There was new cementum along with periodontal ligament and coronal growth of alveolar bone in all groups. Cementum formation was significantly higher in groups 2 and 3 compared to the control group (P < 0.05) with no significant difference between groups 2 and 3. Limited alveolar bone formation was statistically similar in all groups (P > 0.05). It is concluded that both PP and the combination of PP/GTR are effective in the treatment of class II furcation defects in dogs. PP thus appears to be a suitable alternative material in the regenerative periodontal therapy.