Purpose: This study investigated the tensile bond strength between silicone soft liners and processed denture base resin conditioned by sand blasting,methyl methaacrylate monomer and chemical etchant acetone.Materials and methods: 80 samples of polymethyl methacrylate resin blocks were prepared and divided into two groups. 40 specimens were prepared for group A (molosil soft liner) and 40 specimens for group B (tokuyama soft liner). Each group was divided into four sub groups and each one contain 10 specimens according to surface treatment:Sub-group I: (control group) without any surface treatment.Sub-group II: Were sand blasted at the interfacial surface of PMMA blocks by mechanical sandblasting (Micro-V abrasive blaster system) as (figure 15) with 250mM aluminium oxide particles at pressure of 0.62 MPa before application of the soft liner. Sub-group III: were treated with Methyl Methacrylate monomer for 180 s before application of the soft liner.Sub-group IV : will be treated with chemical etchant (Acetone) as (figure 16) for 30 seconds before application of the soft liner.After surface treatment of all specimens, Tensile bond strength of the specimens tested using universal testing machine and compared.Results: the results of present study had revealed that: •Monosil had higher bond strength than tokoyama soft liner regardless of surface treatment. •Regarding Monosil lining material, the ascending order for all surface treatments were sandblasting, Acetone etching, control (without treatment) and etching by MMA respectively.•Regarding Tokoyama conditioning material, the ascending order for all surface treatments were sandblasting, control (without treatment), acetone etching and etching by MMA, respectively.Conclusion: Within the parameters of the materials used and the study design, the following inferences were drawn:•The specimens treated with MMA monomer wetting showed superior and significant bond strength than those obtained by other surface treatments. Followed by wetting with acetone and least for Air abraded specimens with Al2O3 particles.•Among the two silicone liners Monosil Soft liner showed an overall superior performance over tokuyama soft liner.•Both Monosil Soft liner and Tokuyama soft liner had satisfactory bond strength to PMMA denture base resin, which are clinically acceptable.•Failures of soft liner specimens were predominantly adhesive.