Anchorage loss is a critical factor in deteriorating orthodontic treatment results. It can degrade the antero-posterior correction of the malocclusion and decline facial esthetic results. It is defined as the amount of mesial movement of the maxillary molars. The purpose of this study was to evaluate anchorage loss in patients treated with extraction of two maxillary premolars and with labial or lingual fixed appliances. Of the 87 patients, 25 were treated with lingual and 62 with labial appliances. All lingual group patients were non-growing while the labial group consisted of 42 growing and 20 non-growing. Extent of molar movement was evaluated from pre and post-treatment cephalograms and plaster casts. A significant difference was found in anchorage loss between the labial and lingual groups on both cephalometric (p=0.042) and plaster cast (p=0.084). Anchorage loss was greater in the labial group by 1.52±1.41 mm and 1.15+2.06 mm measured from the models and cephalometric radiographs, respectively. No statistical difference was found in anchorage loss between extraction of first vs. second premolars, or growing vs. non-growing patients. The relative stability of the lingual technique is related to incorporation of the second molar bands, using light CL I forces, increasing arch wire stiffness and combining .018 and .022 slot size in the anterior and the posterior dentition, respectively.