The Green apple aphid, Aphis pomi de Geer (Hemiptera: Aphididae), is one of the most common and serious insect pests of apple orchards in Turkey. This species feeds on succulent tissue of trees, which can lead to leaf curling, stunting, distorted tip growth, black-sooty mold, and a vector of some plant viruses. Growers prefer to apply insecticide applications heavily to control the green apple aphid in commercial apple orchards. However, there have not been conducted any research study on insecticide resistance of A . pomi in Turkey. The resistance status of A. pomi populations collected from commercially apple orchards in the Central Anatolia region was investigated to: acetamiprid (neonicotinoid), the specific aphicide pirimicarb (carbamate), beta-cyfluthrin (synthetic pyrethroid), and chlorpyrifos-ethyl (organophosphate) insecticides. All populations were characterised for the first time using polyacrylamide gel electrophoresis to determine the esterase banding patterns. Biochemical assays revealed higher activity of total esterase. This is the first study conducted to determine glutathione S-transferase activity related to the insecticide resistance of A. pomi . It was determined that the resistance levels reached to 14.93 fold to acetamiprid, 3.74 fold to beta-cyfluthrin, 4.19 fold to chlorpyrifos-ethyl, and 4.33 fold to pirimicarb. The present study revealed neonicotinoid, organophosphate, carbamate, and pyrethroid resistance in A. pomi populations from the Central Anatolia Regions of Turkey. It also clearly showed that the enhanced esterase enzyme activity is the main resistance mechanism against carbamate pirimicarb resistance. The present study is the first insecticide resistance study on A. pomi for Turkey.