The applicability and potential advantages of femtosecond laser-induced ionization microscopy in examining biological samples are demonstrated. Highresolution section images of the inner structures and the topographical surface profiles of a piece of unstained onion skin and a human oral epithelium specimen are obtained by collecting the plasma emission signals generated either inside the samples or from air in the vicinity. It is concluded that the high material discrimination capability and the minimum damage effect give this laser-induced ionization imaging technique great potentials in the area of biological imaging and medical analyses.