The necessity for the control and minimisation of unintentional electromagnetic emissions from electnkal systems has long been uppreciated and much skilled effort is spent on EMI suppression. Due to the complexity of the problem, however, very little in the way of CAD tools is available to help the d(esigner. In this contribution, a method is described, bared on the Fifiiite Difference Time Domain technique, whereby the radiation levels from digital circuits may be predicted. Thepredicted results are compared to memrementsfiom some trial configurations.