Introduction: Right portal vein embolization [RPVE] may be used to increase the volume of the future liver remnant [FRL] before major hepatic resection. It is not established whether embolization of segment 4 in addition RPVE [RPVE+4] induces greater hypertrophy of the FRL. Limitations of prior studies include heterogenous populations and absence of correction for patient size. Methods: From 2010 to 2015, consecutive patients undergoing RPVE or RPVE+4 for colorectal liver metastases [CRLM], who had not undergone prior major hepatic resection, were included in this retrospective study. Hospital electronic records [HER] were used to abstract baseline data. Volumetric assessments of segments 2-3 were made on cross-sectional imaging before and after embolisation and corrected for body surface area. Survival was assessed from the HER. Results: Of 105 patients undergoing PVE, 60 met the inclusion criteria. 38 underwent RPVE and 22 underwent RPVE+4. 45 patients had undergone a mean of 5.5 cycles of prior chemotherapy. 13 patients had FRL metastases at PVE and 14 had already undergone subsegmental metastasectomy from the FRL. Assessments of hypertrophy were made at 43.2 ± 28.0 days (mean ± SD) after PVE. RPVE+4 resulted in a significantly greater increase in corrected FRL than RPVE alone (97.0 cm2/m2 vs 62.9 cm2/m2; p=0.008). Multivariate analysis indicated that only RPVE+4 and the presence of left lobe metastases were significantly associated with increased FRL post embolisation. Median survival post PVE was 2.4 years. Conclusion: RPVE+4 results in greater FRL hypertrophy than RPVE alone in patients with CLRM.