To appoint proper strategy for prospective feed efficient pig farming it is wise to shed light on ongoing selection scenarios. Selection based on residual feed intake (RFI) has been proposed to improve feed efficiency, and potentially reduce the environmental impacts accordingly. Data were collected for pigs from the 5th generation of lines divergently selected for RFI (low line, more efficient pigs, LRFI; high line, less efficient pigs HRFI). Individual records for daily feed intake, body weights and body composition were available for about 60 pigs per line. The averages of feed conversion ratio and daily feed intake in the LRFI pigs were 7% lower than the average of the HRFI pigs according to the records. To compare the effects of the difference in feed efficiency on environmental impacts, a parametric model for life cycle assessment (LCA) was developed based on the net energy fluxes. A nutritional growth pig tool, InraPorc® was integrated as a module into the model to embed the flexibility for change in feed, traits and housing conditions, along with simulating individual pig performance. The comparative LCA showed 6% lower environmental impacts for LRFI on average relative to HRFI, considering climate change (CC), acidification potential (AP), eutrophication potential (EP), land occupation (LO) and water depletion (WD). Impacts of CC, AP,EP, LO and WD for 1 kg live weight of pig as the functional unit were 2.61 kg CO2-eq, 44.8 g SO2-eq, 3.37 g PO4-eq, 4.208 m3, 0.0448 m3 for LRFI, and 2.76 kg CO2-eq, 48 g SO2-eq, 3.62 g PO4-eq, 4.44 m3, 0.047 m3 for HRFI,respectively. Parallel Monte Carlo simulation on input parameters demonstrated that LRFI pigs would have a lower environmental impact than HRFI pigs in more than 70% of the calculations, except for water depletion (55% of the calculations). A once-at-a-time sensitivity analysis revealed that environmental impacts are highly sensitive toprotein content of the body and protein deposition. This correspondence between improvement of feed efficiencyand reduction of environmental impacts is very promising for prospective sustainable breeding objectives.