Large congenital melanocytic naevi (LCMN) are associated with an increased risk of malignancy and neurocutaneous melanocytosis (NCM). This Australian study aims to assess both the clinical characteristics of LCMN and the risks associated with it. The authors reviewed medical records of the Sydney Children's Hospital Dermatology Outpatient Clinic for the past 10 years and identified 31 eligible patients. A total of 14 boys and 17 girls with a median age of 0.13 years were assessed; 18 lesions were on the trunk, five were on the head, five were on the lower limbs and three were on the upper limbs. In all 20 patients had satellite naevi (the median number of the satellite naevi was 7.5). The patients were followed up for a median duration of 12 months. Central nervous system magnetic resonance imaging was performed on 19 patients and two (6.5%) were found to have NCM. Biopsies were performed on five patients; one patient (3.2%) was found to have benign proliferative nodules of undifferentiated spindle cells but no patient (0%) was found to have a malignancy. The clinical characteristics for the two patients with NCM and the patient with benign proliferative nodules suggest that the risk of both NCM and benign proliferative nodules may be greater with an increased number of satellite naevi and with the LCMN being larger in size.