An experimental overview of past and present measures on the radiative decays between charmonium states is given. The information from pbarp experiments complements the measurements done in the 80's in e+e- machines. Experimental techniques and sources of statistical and systematic uncertainties on the radiative widths are reviewed. Suppressed transition amplitudes are already accessed from the study of angular distributions: recent results from e835 will be shown. To fully exploit the amount of information yielded by the E760/E835 experiment, a new generation of data from e+e- is needed. Future prospects to achieve 5% uncertainty on the full experimental pattern, where theory predictions at order O(beta^4) and O(alpha_s^2) can be tested, are given.