Using a modification of the Babcock photographic technique, it has been possible to make measurements of the day to day growth of the fingernail in human subjects. There are marked individual variations in the rate of growth at all ages, but for the same individual and the same nail the rate of growth is relatively constant and can be used to study the effect of various physiologic and pathologic disturbances. Preliminary observations indicate that nail growth is unfavorably affected in certain disease states, notably measles and nephrosis. Malnutrition and certain dietary restriction were not found to affect this parameter appreciably. Growth of the nails was followed for 10 days after death and was found to be measurable, the rate exceeding that noted during a severe attack of measles.