The findings of some 26 papers covering the results of Andresen and Fränkel appliances, as analysed from cephalometric radiographs, are reviewed. These findings show a high degree of consistency. They have been combined to produce larger samples and compared with a control group produced from reports of untreated Class II division 1 individuals, with consequent gains in statistical significance. Generally, there is no appreciable holding back of maxillary advancement in either group (although a slight relative reduction in the angle SNA). There is a slight mean increase in mandibular growth, mainly in a vertical direction. This seems similar to that reported by several authors in conventional appliances. There is a wide variation in response.