Here, we describe a method for obtaining thin cross sections of Arabidopsis thaliana roots without fixation and embedding. Roots were grown in pinholes made in a solidified growth medium, and cross sections were prepared without pretreatment. Using this method, we detected unique distributions of two polar-localized proteins-green fluorescent protein (GFP)-tagged BOR1 and NIP5; 1-with less sample preparation time than conventional methods. This method is simple, rapid, and yields high-quality cross-section images that are free from artifacts commonly associated with embedding or the sample preparation procedures used in many conventional methods.