The purpose of this study was to determine dental and skeletal effects of compressed nickel-titanium coil springs used for distal movement of the maxillary molars. Initial and follow-up cephalometric radiographs were taken of 8 patients (2 males and 6 females) in the late mixed or permanent dentition stage with Class 11 malocclusion. Nickel-titanium coil springs exerting a near constant force of approximately 250 g were compressed against the maxillary molar tubes by Gurin locks. The mean treatment time was 6.95 +/- 0.2 months. Dental and skeletal changes were determined as follows: The mean maxillary first molar distalization was 5.44 mm (right) and 3.75 mm (left), with a mesial tipping of 11.56 degrees (right) and 11.34 degrees (left). Anchorage loss occurred as defined by mesial movement of the first premolars and proclination of the central incisors. Vertical dental and skeletal dimensions were not affected.