Abstract: A tamperproof lid for a container, in which a toothed ring portion must be substantially completely removed from its connection to the remainder of the lid and also from contact with the rim of the container in order to open the container, thus providing protection against tampering with the contents of the container. The lower portion of the lid outer periphery is provided with toothed or segmented sections extending around the circumference of the lid. Upon an attempt being made to raise the lid, the teeth will engage the lower surface of the container rim in a tight, firm construction which tends to hold more tightly as any attempt is made to remove the lid. Thus the lid of the invention may not be removed without destroying the seal which the lid makes with the rim of the container.