Background: The front-line treatment of advanced NeuroEndocrine Neoplasms (NENs) depends on clinical and pathological factors but there are no standard second-line therapies. Methods: Metastatic NENs patients were treated at the ENETS (European NeuroEndocrine Tumor Society) center of excellence of Naples (Italy), from 2014 to 2017 with second-line metronomic temozolomide, 75 mg/m2 per os “one week on/one week off”. Toxicity was graded with NCI-CTC criteria v4.0; objective responses with RECIST v1.1 and performance status (PS) according to ECOG. Results: Twenty-six consecutive patients were treated. Median age was 65.5 years. The predominant primary organs were pancreas and lung. Grading was G2 in 11 patients, G3 in 15. Eleven patients presented with PS 1 and 15 with PS 2. The median time-on-temozolomide therapy was 12.2 months (95% CI: 11.4-19.6). No G3/G4 toxicities were registered. Complete response was obtained in 1 patient, partial response in 4, stable disease in 19 (disease control rate: 92.3%), and progressive disease in 2. The median overall survival from temozolomide start was 28.3 months. PS improved in 73% of patients. Conclusions: Metronomic temozolomide is a safe and active treatment for G2 and G3 NENs. Prospective and larger trials are needed to confirm these results.