An improved system and method are disclosed for non-destructively determining the thickness and uniformity of an anti-tamper coating on a sensitive electronic part, such as, for example, an integrated circuit, multi-chip module, or other type of electronic device, component or equipment. The system includes an anti-tamper coating thickness measurement probe with a highly collimated beta radiation source and a Geiger-Muller tube sensitive to beta radiation arranged in close proximity to the beta radiation source. The probe is placed on or in close proximity to the anti-tamper coating on the part, so that the beta radiation electrons penetrate the coating material and are reflected back (back scattered) toward the beta radiation source and the Geiger-Muller tube. The Geiger-Muller tube collects the electrons from the back scattered radiation.