Although there are numerous publications on bilateral non-compliance molar distalization appliances, there is limited information on problems such as asymmetrical unilateral Class II malocclusions. The aim of the present investigation was to examine the distalization of molars unilaterally in patients with a unilateral Class II molar relationship utilizing a Keles Slider, designed without a bite plane. Ten girls (mean age 13.94 +/- 2.13 years) and seven boys (mean age 13.12 +/- 1.51 years) comprised the study material. Following insertion of the appliance, the patients were seen monthly and the screw was reactivated every 2 months. After a super-Class I molar relationship was achieved, the appliance was removed and the molars were stabilized with a Nance appliance for 2 months before the second-phase of orthodontic treatment. The Nance appliance was maintained in the palate until the end of canine distalization. Lateral cephalometric radiographs were obtained before and immediately after insertion of the molar distalizer. The results showed that the maxillary first molars were distalized bodily on average by 2.85 mm. The maxillary first premolars moved forward bodily 2 mm and were extruded 2.03 mm. In all, 1.32 mm of protrusion, 1.12 mm of extrusion, and 1.79 degrees of proclination of the upper incisors were observed. The mandibular incisors and mandibular molars erupted 0.83 and 0.95 mm, respectively. The unilateral Keles Slider distalized molars successfully to a Class I molar relationship.