Space maintaining extraction on one side is a controversial point in orthodontics, yet relevant references in literature are only few and far between. The author has summed up the attitudes towards the unilateral Space maintaining extraction by levelling. Among other things, he emphasizes the importance of avoiding extraction on one side, however when in one quadrant there is smaller room than that of a pre-molar would occupy, an extraction as a concession might be made. When making extraction distal removal is indicated (in such cases the extraction of a molar is also possible) and to avoid non-preferable deformities very soon a strong and rigid are needs to be applied. Teeth in situations which are not meant to be changed, should be fixed. Care should be taken that the central line will not be displace to the direction of extracting. Generally speaking, it is not possible to establish an excellent occlusion in the case of unilateral extraction. After the treatment, the wisdom tooth which pushes forward might cause the displacement of the central line. In the case of unilateral extractions, the patient should be reported on the visible consequences that might occur.