Combustion processes involved in internal combustion engines greatly depend on the characteristics of the spray. This study is focused on the comparison of three different techniques used for spray drop sizing. A diffraction granulometer (DG), a phase Doppler particle analyzer (PDA), and image analysis (IMA) have been used to characterize gasoline sprays produced by gasoline injectors of direct-injection type. Whereas studies comparing drop-sizing techniques found in the literature are mainly dealing with steady flows, attention is paid here to the unsteady nature of the spray. The differences in the measurement volumes of the different techniques are also considered. Since these diagnostics do not measure exactly the same kind of distribution, both PDA and IMA measurements were converted to concentration-dependent volume-weighted drop-size distributions to be compared to DG. The Sauter mean diameter D-32 is used to characterize the spray for different time and position of the measurement volume in the spray. Velocities and droplet morphology are also considered in order to understand the behavior of the spray. The comparison between the three techniques shows a good agreement since attention is paid to the sample volume and to the acquisition time of each technique.