Although higher treatment pressures have the potential to improve preservative penetration, higher pressures may possibly result in greater reduction in mechanical properties. The present study evaluated the effect of treatment pressure on the treatment quality and mechanical properties of red pine (Pinus resinosa Ait.) lumber. End-matched sections of red pine lumber were treated with an ethanolamine copper preservative at pressures of 1,207 kPa (175 psi), 1,379 kPa (200 psi), or 1,551 kPa (225 psi). Preservative uptake and penetration were measured, and small clear specimens were subsequently cut from the specimens for evaluation of bending properties. The average percentage of sapwood penetration increased slightly with increasing pressure, and this difference was statistically significant between the 1,207-kPa (175-psi) and 1,551-kPa (225-psi) pressures. In comparison to untreated specimens, treatment at all pressures caused small reductions in modulus of rupture and work to maximum load. However, there were no significant differences in bending properties between the pressures evaluated, indicating that higher pressures can be used without additional sacrifice of wood properties. These treatments were conducted at ambient temperature, and the findings do not necessarily apply to treatments conducted at elevated temperatures.