Purpose: This study was to assess the accuracy of the vinyl siloxanether impression in two different span lengths (short, long). Material and Methods: Two stainless steel master model designs were fabricated. The first model simulated a short span clinical situation and the second, a long span case. Each model consisted of two stainless steel dies simulating prepared abutments to receive full coverage fixed partial denture (FPD). Ten impressions of each material Vinyl polysiloxan(VPS) and Vinyl siloxanether (VSE) were made for each of the two models. Results: There was no significant difference in the performance of the addition silicone versus (VSE) impression materials in short span design as for as dimensional accuracy is concerned, and there was significant difference in the performance of the addition silicone versus (VSE) impression material in long span design. (The VSE demonstrated significantly higher dimensional accuracy than did VPS). Conclusion: the VSE monophase one-step impression technique was the most accurate for the fabrication of stone models.