This paper discusses the impact on package integrity of high-altitude shipments of glass and plastic bottles. High altitudes are encountered when trucks travel over mountain passes and when cargo and feeder aircraft transport packages in nonpressurized or partially pressurized cargo holds. This is the second research study conducted on liquid product shipments. The first was done on liquid hazardous material combination packaging. The testing of pharmaceutical packaging is critical since the integrity of the product may be compromised during shipping and handling. Current shipping tests performed in labs do not account for simultaneous pressure changes and vibration. This study shows that packages currently being used for shipments of liquid pharmaceuticals that are tested to existing ASTM and ISO shipping tests are often inadequate, and can result in a significant number of leakers. Testing under combined vibration and pressure is necessary to ensure integrity.