A system is described for automatic measurement of contrast sensitivity functions (c.s.f.). The measuring technique is based on the Von Bekesy tracking method. One c.s.f. can be measured in 10 min. The stimuli (sinewave gratings) are generated on a t.v. monitor screen. The stimulus parameters (spatial frequency, contrast and field size) are controlled by a microprocessor. The results are plotted in an easily interpretable from, giving the c.s.f. of both eyes together with the radio between the contrast sensitivity of the two eyes. Clinical measurements on amblyopic patients are described by way of illustration of the application of the system.