204 hours of high-quality measurements of 4 CVn during 32 nights were obtained with the 0.75 m Automatic Photolectric Telescope (APT). The two comparison stars measured agreed to ±2.7 mmag per single measurement in Stromgren y and ±3.0 mmag in v. It is shown that APT's can be used successfully for the study of stellar nonradial pulsation at the millimag level. An analysis of the multiperiodicity of 4 CVn revealed the presence of 19 simultaneously excited pulsation frequencies. This presents a considerable increase from the 7 frequencies found during a previous campaign of the Delta Scuti Network. The previously known frequencies were confirmed with amplitude variability on a time scale of years.