Our aim was to evaluate clinical and pathological features in prognosis of thymoma patients with particular emphasis on patients with myasthenia gravis (MG). From 1995 to 2010, 140 thymoma patients (women/men: 63/77) with a median age of 46 years (11-80 years) were admitted to our institution. According to World Health Organization (WHO), there were 23 (17%) type A, 12 (9%) type AB, 24 (17%) type B1, 42 (31%) type B2 and 36 (26%) type B3. The distribution of Masaoka stages I, II, III and IV was 24 (17%), 71 (51%), 18 (13%) and 27 (19%), respectively. MG coexisted in 61% of patients. After a mean follow-up of 34 months (1-158 months), 102 (73%) patients are alive and well while 14 (10%) are alive with disease. Twenty-three patients (16%) have died, only 9 died of thymoma. In univariate analyses, completeness of resection (P < .001), WHO histology (P = .008), Masaoka stage (P < .001) and MG (P = .002) were significant prognostic factors for progression-free survival (PFS). Young age (P = .008); Masaoka stages 1 and 2 (P = .039); WHO types A, AB and B1 (P = .031); complete resection (P = .024) and presence of MG (P = .05) significantly correlated with overall survival (OS). In multivariate analysis, Masaoka stages 1 and 2 (P = .038) and presence of MG (P = .01) were significantly correlated with a longer PFS; MG (P = .021) and WHO subtype (P = .022) were found to be significant prognostic factors for OS. Adjuvant radiotherapy improved neither OS nor PFS in completely resected stage 2 thymoma. Masaoka staging, WHO and MG are major determinants of prognosis in Turkish thymoma patients. Additionally, radiotherapy did not provide survival advantage to stage 2 patients with complete resection.