Abstract: Categories of canine lymphocytes forming rosettes with guinea pig erythrocytes (E-RFC) were studied.The incubation of canine lymphocytes at 37℃ increased E-rosette formation.The percentages of Sig positive cells in E-RFC were similar to those in total lymphocytes.In mixed E-EAC (guinea pig erythrocytes-sheep erythrocytes coated with antibody and complement) rosette assays,a portion of canine lymphocytes having both E and complement receptors has been detected.No significant difference was found in the mean percentages of E-RFC between total lymphocytes and EAC-rosetting ones.On the basis of these results we assume that the E receptors are present on a part of T cells and also on some B cells.Thus,the E-rosette assay cannot be used for detection of canine T cells.