Abstract: A container for packaging vials containing diagnostic specimens, or the like, which are to be mailed or transported. The container includes an open-topped plastic cylinder with an integral bottom wall having an upper section of the sidewall which is of a reduced diameter and includes opposed outwardly projecting lugs for engaging complementary slots in a cylindrical cap for the container. The upper section of the sidewall further includes a radial groove which accommodates an elastic O-ring for providing a leak proof seal for the container. The cap slides over the upper section of the sidewall and sealingly engages the O-ring to provide a leak-proof seal. The container is further provided with an open celled plastic foam insert which die-cut to accommodate up to three vials.