This thesis considers the criterion of minimizing total job tardiness in a flowshop system in which no queues are allowed at any intermediate storage. Several models such as tow-machine flowshop problem, three-machine flowshop problem with the first machine dominating the second machine, and multiple-machine flowshop problem with machines dominated in either increasing or decreasing order are investigated. Some necessary conditions to determine the sequential order between a pair of adjacent jobs are derived. For all the models except for the model with all machines dominated in increasing order, branch and bound solution procedures are exploited. For the model with all machines dominated in increasing order, a heuristic solution procedure is derived. Various numerical examples are presented to illustrate the solution procedures.