Registers of quality can be used to ensure that health care recommendations are followed, to verify the logistics of care and serve as a basis for research when population based data are needed. Validation of quality is important and is the fundament of accurate interpretation of collected data. In the present validation of sentinel node biopsy (SN) for malignant melanoma in Southern Sweden during 2013, we see that registration is incomplete in 4% of the cases. In some of the cases it appears that treating physicians may be unaware of treatment recommendations regarding SN in melanoma.