The aim of the European Reference Network for Rare Endocrine Disorders (Endo-ERN) is to ensure equal access to high-quality care for all those affected by a rare endocrine condition across Europe, such as a disorder/difference of sex development (DSD), both for children and adults. Although differences in resources, health care systems, and health insurances between the European countries are challenging and require political action, a European laboratory network within Endo-ERN could improve the diagnostic process in individuals with DSD, building on the work done by previous European collaborations such as the COST action DSDnet. In close collaboration, clinicians and laboratory specialists must make every effort to standardize diagnostic protocols, achieve necessary harmonization of various laboratory tests, e.g., the hCG stimulation test, and implement an external quality control system. This should ideally result in comparable quality across the network centers allowing the sharing of reference values. This would not only improve patient care but also greatly facilitate research.