We propose and test experimentally a new way of probing vertical shear of ocean surface currents by means of a single frequency VHF radar. The key idea is to use additional information provided by the so called secondary peaks in radar echo spectra which appear due to nonlinearity. Results of the field experiment carried out in the Rho⁁ne's delta show that the new method does enable one to probe the vertical shear with a reasonable accuracy and has potential for further development. ¿ 2001 American Geophysical Union