Abstract: An adjustable travel bag which includes a main bag body having a front open side and an endless, strap-like folding collapsible coupling panel around the front open side, and an auxiliary bag body openably fastened to the coupling panel of the main bag body by a main zipper to close/open the front open side of the main bag body, wherein the coupling panel of the main bag body has two rows of interlocking teeth fixedly mounted along two opposite side edges thereof and unfastenably fastened together by a slide to secure the coupling panel in a folded up condition to minimize the holding space of the main bag body.