AbstractHealing events after nonsurgical periodontal therapy in patients with periodontal pockets 4–7 mm deep were investigated. Incisors, cuspids and premolars in 15 patients were treated by plaque control and supra‐ and subgingival debridement using hand or ultrasonic instruments in a split mouth approach. The results were evaluated by recordings of plaque scores, bleeding on probing, probing pocket depths and probing attachment levels. All these parameters were improved during the initial 4–5 months after start of therapy. Little change occurred during the rest of the 13‐month observation period. No difference of results could be observed comparing hand and ultrasonic instrumentation or comparing the results of two different operators. Initially a total of 106 sites demonstrated probing pocket depths ≥ 6 mm. At 13 months only 13 such sites were observed. The apparently successful results of conservative treatment of patients with 4–7 mm deep pockets in the present study raise the question to what extent nonsurgical therapy is feasible also in patients with severely advan