The aim of the present study is to report our experience with lymphatic mapping (LM) and sentinel lymph node biopsy (SLNB) in a selected group of patients with thin primary cutaneous melanomas. Fifty patients (22 females and 28 males; mean age, 57.8 years; range, 30–77 years) with a mean tumor thickness of 0.63 mm (range, 0.24–1.00 mm) underwent LM/SLNB. Twenty-eight (56%) of them had Clark level II, 20 (40%) had Clark level III, and two (4%) had Clark level IV. Tumor ulceration was present in two patients (4%) and histological regression in 35 patients (70%). Sentinel lymph node (SLN) metastases occurred in two of 50 patients (4%). The first case was a 0.88-mm thick, Clark level III, non-ulcerated superficial spreading melanoma of the trunk, without any regression. The second case was a 0.95-mm thick, Clark level IV, non-ulcerated superficial spreading melanoma of the neck, with regression. Both patients were disease-free 76 and 50 months after the SLNB procedure and followed complete lymph node dissection, respectively. The patients with negative SLN were disease-free after a median follow up of 44 months (mean, 43.2; range, 15–84 months). Published data and our experience suggest that LM/SLNB is not routinely indicated for melanomas less than 0.75 mm. Our results confirmed the accuracy of the new American Joint Committee on Cancer/International Union Against Cancer criteria, in which SLNB is required for thin melanomas less than 1.0 mm when they have ulceration or Clark level IV and V invasion.