IntroductionVideo-assisted thoracoscopic surgery (VATS) was not considered for the treatment of primary mediastinal tumors of large sizes or with local invasion.AimTo investigate the clinical outcomes of VATS for large and invasive mediastinal tumors.Material and methodsOne hundred and thirteen patients with primary mediastinal tumors were treated by VATS. Twenty-nine patients had bulky tumors (diameter > 6 cm) and 5 patients had invasive tumors. Clinical data were documented and compared.ResultsNo patients suffered from any complications after VATS. No relapse or metastasis occurred in the patients with bulky tumors, while 1 patient with invasive thymoma suffered a relapse after VATS. The 2-year disease-free survival and overall survival in patients with bulky tumors were 100% and 100%, while those in patients with invasive tumors were 75% and 100%. There were no differences in hospital stay after VATS between the patients with bulky tumors and smaller tumors, nor between the patients with invasive tumors and non-invasive tumors. Patients with bulky tumors lost more blood than those with smaller tumors, while more blood loss occurred in patients with invasive tumors than non-invasive tumors. Longer operative time was needed for patients with bulky tumors and invasive tumors. Mediastinal tumors with large size or invasion should not be contraindicated for VATS. The prognosis of such patients treated with VATS was comparable to that of traditional open surgery.ConclusionsVATS is a safe and effective procedure for large and invasive mediastinal tumors.