Introduction: Long-term data on outcomes of operable stage III NSCLC are scarce. Methods: Individual patient data from 368 patients enrolled in one phase III and two phase II trials were pooled and outcomes after applying the eighth (denoted with an asterisk [*]) versus the sixth TNM staging edition were compared. Patients were treated with either preoperative radiotherapy following 3 cycles of induction chemotherapy (trimodal) or neoadjuvant chemotherapy alone (bimodal). Results: With the sixth version, the 5- and 10-year survival rates were 38% and 28% for stage IIIA, respectively, and 36% and 24% for stage IIIB, respectively. Factors associated with improved 5-year overall survival were younger age, R0 resection, and pathologic complete remission (pCR) (p = 0.043, p < 0.001 and p = 0.009). With the eighth TNM staging version, 162 patients were moved from stage IIIA to IIIB*. The 5- and 10-year survival rates were 41% and 29% for stage IIIA*, respectively, and 35% and 27% for stage IIIB* patients, respectively. There was no difference in the bi- versus trimodal group with regard to median overall survival (28 months [95% confidence interval (CI): 21-39 months] and 37 months [95% CI: 24-51 months], p = 0.9) and event-free survival (12 months [95% CI: 9-15 months] versus 13 months [95% CI: 10-22 months], p = 0.71). Conclusions: We showed favorable 10-year survival rates of 29% and 27% in stage IIIA* and IIIB*, respectively. Younger age, R0 resection, and pathologic complete response were associated with improved long-term survival. Outcomes using the sixth versus eighth edition of the TNM classification were similar in operable stage III NSCLC.