This paper deals with the assembly line balancing problem. Within this context, the objective is to show that nowadays, in many practical cases, it is possible, even in large problems, the application of exact solution procedures (in this case, integer programming). This is accomplished by means of two case studies in big companies of São Paulo State, which presents large assembly line balancing ... [Show full abstract] problems (lines with 80 and 104 tasks). In one of these cases one constraint unpublished on literature was included in the model to adapt the model to the real situation. This constraint accounts to those cases in which the assembly line has both manual and automatic tasks. The results were very good, and a reduction of more than 10% was attained in the number of workstations required on the assembly line.