This study evaluated the resistance to plastic deformation under a flexural load (PLf) of a denture base material relined with four different types of denture reline materials. A heat-processed poly(methyl methacrylate) denture base was relined with varying thicknesses of denture reline materials and subjected to a flexural load. The flexural load at the proportion limit (PLf) was recorded. The PLf of the bulk denture base and denture reline materials were also measured for comparison. All relined denture bases showed significantly lower PLf than the bulk denture base. Generally, the PLf of the reline-denture base composite progressively decreased with an increasing proportional thickness of the reline material