Abstract: A tamper indicator for placement over valves and other regulating type devices used on storage containers to detect any unlawful operation of the valve or other device. This indicator has a sleeve-like body, closed at one end, for encasing the valve or other device. A locking bar is passed through openings in the body near the open end, this bar positioned so as to engage the base of the valve or other regulating device. One end of the bar has a restriction to prevent passage of that end through the openings, and the other end of the bar is provided with an aperture to receive a seal member. This seal member must be destroyed for removal. A broken seal member thus indicates tampering. By providing a unique indicia on the seal member, any attempt to install another seal member after tampering has occurred can be detected. The device of the present invention is of particular value when used as a tamper indicator on valved containers of uranium hexafluoride or other controlled substances.