This paper discusses the multiblock (MB)-split load bal ancing tool for structured-grid multiblock Navier-Stokes solvers running on parallel computers of MIMD type. Many load-balancing algorithms and tools are available for com putational fluid dynamics solvers using unstructured meshes. Most load-balancing algorithms for block-struc tured meshes only aim at distributing the initial blocks of the mesh over the processors, without splitting any blocks. A more flexible load-balancing technique uses domain decomposition and splits blocks into smaller blocks. One of the problems with this approach is the complexity of updating block connectivity boundary conditions. The three load-balancing algorithms are implemented and some results for realistic test cases are presented.