Reverse micellar extraction of various proteins of large molecular weight and oligomeric proteins, as well as small ones, was carried out using conventional AOT reverse micellar extraction systems at various pH values. The conformational change of the proteins by electrostatic interaction with AOT wits also measured using a CD spectrum. Extraction behavior and conformational change of the proteins were discussed from their electric charge properties and electrostatic interaction between protein and AOT. Most of the proteins were effectively extracted into the reverse micellar phase at around zero surface net charge. Formation of aggregates and denaturation of proteins were observed in the region of positive net charge higher than 10.