Cytologic methods for detection of early cancers of the uterine cervix, lung and various other organs are discussed. The scraping smear method using a spatula is more effective than the cotton swab or vaginal pool smear method for detection of preinvasive intraepithelial lesions, such as, carcinoma in situ and dysplasias of various degrees of the uterine cervix. The use of sputum specimens pooled for three to five days is recommended for cytologic examination in population screening of lung cancer. Good cytopreparatory techniques, suitable screening and cytodiagnostic classifications of malignancy are also described and emphasized, especially, the importance of properly fixed cytologic material for correct cytopathological diagnosis.