The effect of lead magnesium niobate titanate (PMNT) particle size on the dielectric and ferroelectric properties of PMNT-Portland cement (PC) composites was investigated. PMNT of various particle sizes (75-425μm) were used at 50% by volume to produce the composites using the mixing and pressing method. Dielectric properties at various frequencies (0.1-20 kHz) and ferroelectrics behavior of the PMNT-Portland cement composites were investigated at room temperature. The results show that the dielectric constant of PMNT- Portland cement composite are found to increase (εr = 154 for particle size 75 μm and εr = 275 for particle size 425 μm (at 1 kHz)), while dielectric loss decreased with increasing particle size of ferroelectric PMNT ceramics. Furthermore, the "instantaneous" remnant polarization (Pir) of composites was found to increase with increasing PMNT particle size.