Various methods of measuring deposits of spray oils are reviewed. All methods except one colorimetric analysis involve extraction of the oil from the sprayed surface with a suitable solvent, evaporation of the solvent, and either volumetric or gravimetric measurement of the extracted oil. Both whole leaves and disks of known area have been used. Although the distribution of oil may not be uniform over The whole leaf, the disk method of sampling is considered adequate for measurement of relative results. Rapid loss of oil following application of field spray necessitates either prompt extraction or storage of samples at low temps. It is doubtful whether relative deposits in field sprays can be inferred directly from laboratory measurements, since differences in the surfaces or conditions of application may change the relative quantities of oil deposited by different sprays.