Intact yeast cells Saccharomyces cerevisiae can be efficiency transformed by combined effect of polyethylene glycol and CaCl₂. This study had been undertaken to determine the effect of using 24% (PEG) in 0.4M manitol and 30 mM MgCl₂, 0.3% CaCl₂ and the combination of the two individuals.                 The results showed that (PEG) or CaCl₂ alone caused a few transformants and a low of transformation percentage. In addition, (PEG) gave higher transformants and transformation percentages more than that of CaCl₂ as it facilitates the entrance of DNA into the yeast cell walls. In contrast, the combined effect of (PEG) and CaCl₂ in the same condition reproducibly yield the maximum number of transformants and transformation percentages. Data also revealed that the transformation percentage was 2.5 fold higher than values given in individual treatment.                 It is obvious that higher culture viscosity were produced by transformants isolates from combined effect and CaCl₂ experiments. This observation was due to Ca⁺⁺ activated dextran sucrose by increasing the V_max and decrease the K_m of sucrose polymerase. In this study, transformants isolates seem to been differ in their ability to express dextran gene(s). This means that the events at one molecule can affect event at a distant location by different ways on the same molecule.