Abstract: Hollow plastic containers provided with a narrow opening and a body having a base and at least one side wall extending longitudinally between the narrow opening and the base, such as bottles or similar, are obtained from preforms by stretch blow molding. A blend of polyethylene terephtalate (PET) and polytrimethylene terephtalate (PTT), with a weight proportion of PTT in the range 5-50% is injected to obtain the preform. During the stretch blow molding step, the multi polyester preform undergoes longitudinal stretching at a longitudinal ratio of between approximately 3.5 and 6 and radial stretching at a ratio of between approximately 4 and 9. The body of the preform is subjected to an overall stretching ratio included between 16 and 50, whereby the weight of the container produced by stretch-blow molding may be reduced.