A flow line consists of a sequence of workstations through which one or more products move one way in order to be processed. Designing such a line represents a long-term decision problem involving different crucial decision stages, often solved iteratively because of their complexity. Line balancing problem is one of them; it mostly deals with assigning the set of indivisible units of work (named tasks or operations) to a sequence of lineally ordered workstations. In this paper, we present a brief overview of flow lines balancing problems recently appeared in the literature, which try to expand the core optimization problem dealing with assigning tasks by solving it jointly with other decision problems, such as process planning, configuration design or detailed line scheduling. In spite of the fact that, previously, the most attention was paid for the balancing problems concerning the assembly systems, the approaches and formulations of flow line balancing in machining environment are analyzed as well.