4081 Background: Radical resection of LM is the only chance of cure for liver-only mCRC pts. Besides the evaluation of technical resectability, several factors must be taken into account for the evaluation of recurrence risk. Among them we should consider the Fong Risk Score and its modified version, including RAS/BRAF status (Brudvik’s score). Tumor sidedness is an important prognostic factor in CRC. The impact of PT site on the outcome of LM resection is still debated. Hence, we retrospectively analysed mCRC pts, underwent to radical LM resection at our Institution, investigating the impact of PT site on DFS and OS. Methods: Liver-only mCRC pts underwent to radical LM resection were included. The association of PT site with DFS and OS was evaluated. The following variables were collected: gender; age (≥ vs < 75 years ); ECOG PS; CEA baseline level; PT site; RAS and BRAF status; mucinous histology; grading (G1-2 vs G3); RECIST response during preoperative treatment; resected PT; synchronous vs metachronous; number of LM; bilobar vs unilobar LM; LM diameter ≥ 5 cm; R0 vs R1 resection. Univariate and multivariate analyses for DFS and OS were performed. Results: A total of 463 liver-only mCRC pts underwent to radical LM resection were included. Seventy (15%) pts had a right-sided (r-s) tumor and 393 (85%) pts a left-sided (l-s) tumor. R-s CRC pts more often had RAS/BRAF mutations in comparison to l-s tumors (76% vs 37%; p < 0.0001). Median DFS and OS was 13.1 and 41.6 months, respectively, in r-s CRC vs 16.0 (p = 0.65) and 62.2 months (p = 0.033), respectively, in l-s tumors. At the multivariate analysis no significant association with survival parameters was shown for tumor sidedness. At the multivariate analysis, R0 resection was independently associated both with better DFS and OS; RAS/BRAF wt CRC and resected PT were significantly associated with improved OS. Considering all wt CRC pts (N = 237), 14 (6%) pts had r-s tumor and 223 (94%) l-s tumor. No significant association of tumor sidedness with survival was shown (DFS r = 10.0 vs l = 16.0 months, p = 0.62; OS r = 40.3 vs l = 66.2 months, p = 0.12). Conclusions: Our results showed that a significant smaller proportion of r-s CRC underwent to radical LM resection, indirectly confirming its worse prognosis. Among radically resected pts, r-s CRC was associated to a shorter OS (significant) and DFS (not significant) compared to l-s CRC, but it was not confirmed at the multivariate analysis. We can conclude that right PT site should not be considered as a contraindication for radical LM surgery, when feasible.