Objectives - The objective of this study is to describe how the departmental Maternal and Child Health (PMI) services that participated in the Elfe-PMI survey conducted the health checkup for 3- to 4-year-old children enrolled in preschool (BSEM). Methods - The Elfe-PMI survey was conducted among children born in 2011 and enrolled in the younger and middle preschool classes in 30 participating departments in metropolitan France during 2014–2016. The frequencies of the various screenings offered during the BSEM were described and analyzed according to demographic data, socioeconomic indicators, and the implementation methods of the BSEM. Results - There are regional disparities in how the health screening for 3- to 4-year-olds conducted by the PMI operates. These disparities are not linked to sociodemographic factors such as socioeconomic vulnerability, access to care, or the resources available to the PMI. They affect the number of children screened and the methods used for screening. Conclusion - The varied organization of the BSEM appears to reflect departmental choices. A national-level review of this program should be conducted to ensure equitable access to screenings for 4-year-olds across the entire country.