Assuming that the compliance for the traditional method with an invitation letter is equal to 15% (Giorgi Rossi 2010), the present study is designed to be able to detect an absolute difference of 1.5% or greater in the attendance rate with a conventional levels of power (80%) and significance (95%, one side test) with a planned sample size of 8000 women. Assuming a sample size equal to 2000 women for each sampling devices, a significant difference equal to or greater than 4.0 percentage points more or less , considering a HPV positive rate of about 21% (Giorgi Rossi 2010) with same power and significance.