Abstract: A lyophilization bag is provided herein for containing a solution in a lyophilizer during lyophilization. The lyophilization bag includes a body having a flexible base member, and a flexible top member. The base member and the top member, collectively, at least partially encompass an interior volume of the body. A first portion of the interior volume is defined between at least portions of the base member and a reference plane located spaced from the at least portions of the base member, the first portion of the interior volume defining a volume corresponding to the initial volume of the solution. A second portion of the interior volume is defined between the reference plane and at least portions of the top member. At least one port defining an opening is in communication with the second portion of the interior volume.