Background: AJCC comprises two markers (Breslow thickness and ulceration) to subdivide stage II CM patients into groups with relatively low, average, or high risk of death. Recent updates of clinical guidelines (NCCN, AAD) suggest that patient management be further tailored to an individual prognosis, e.g. through gene expression profiling (GEP). The aim of this single center study was to clinically validate a prognostic GEP-based risk score (MelaGenix) for stage II CMs. Methods: All obtainable, formalin-fixed paraffin-embedded (FFPE) primaries of AJCC stage II CMs from the Central Malignant Melanoma Registry of Germany archived in Tuebingen were included. Study hypothesis and protocol were prospectively formulated. Tumors were analyzed blinded to clinical outcome (data exchange overseen by independent data clearing house) to determine GEP low- vs. high-score groups with a pre-specified GEP score cut-off (≤0.00 > ). Melanoma specific survival (MSS) was evaluated by Kaplan-Meier (KM) analysis and prognostic performance was assessed by multivariate Cox regression. Results: Study cohort comprised 245 stage II primaries (IIA/B/C n = 118/78/49). Median follow-up was 40 months, 5y/10y MSS was 86/75%, median thickness was 3.0 mm, 142 tumors were ulcerated. GEP low-score group had 5y&10y MSS of 92%; GEP high-score group had 5y/10y MSS of 82/67%. KM log-rank was significant (p = .018); GEP score contributed independent prognostic information in multivariate Cox regression (p = .024 HR = 1.45 [1.05 – 2.00]) vs. covariates pT categories (p = .002 HR = 1.59 [1.19 - 2.13]) and age (p = .001 HR 1.05 [1.02 - 1.09]). Conclusions: MelaGenix has been validated as an independent predictor of MSS in stage II patients and refines prognosis beyond AJCC. MelaGenix could serve as an important prognostic decision tool regarding patient management, especially whether adjuvant systemic treatment is appropriate – once drugs become available. It seems reasonable to include this score in future clinical trials.