We present optical characterizations of live amphibian erythrocytes by utilizing quantitative phase imaging. Without any labeling or preparation procedures, 3-D refractive index tomogram and 2-D phase delay of amphibian erythrocyte were measured using Mach-Zehnder interferometry. Refractive index value in 3-D tomograms represent structural and chemical features of an erythrocyte and the nucleus. In addition, membrane fluctuation of amphibian erythrocytes was measured to be more profound than that of human erythrocytes.