This experiment tested the hypothesis that pigs challenged with an enterotoxigenic strain of E. coli (ETEC) would require a higher sulphur amino acids (SAA) to Lys ratio (SAA:Lys). Pigs (n = 120) weighing 7.4 ± 0.52 kg (mean ± SD) and weaned at 27 d (Pietrain genotype, mixed sex) were stratified into 1 of 6 treatments based on weaning weight, sex and genotype for the F4 fimbria receptor (n = 20). Five diets were formulated with increasing ratios of standardised ileal digestible (SID) sulphurSAA:Lys. Pigs were housed in pens of 4 during an adaptation period of 6 d after which time pigs were housed individually. Pigs fed different SID SAA:Lys levels were infected with ETEC (5 mL, 1.13 × 10⁸ CFU/mL, serotype O149:K91:K88) on d 8, 9, and 10 after weaning. The sixth diet, which contained 0.55 SID SAA:Lys and corresponded to current NRC recommendations, was allocated to 2 groups of pigs either with or without ETEC infection, and was considered as the infected or non-infected control group respectively. Pigs were fed Phase 1 diets (10.2 MJ NE, 1.2% SID Lys) ad libitum until d 15 after weaning. Phase 2 diets (10.2 MJ NE, 1.1% SID Lys) were fed ad libitum for the following three weeks. Diets did not contain any antimicrobial compounds. Corrected SID SAA:Lys determined based on analyzed amino acid content and the respective standardised ileal digestibility of ingredients were found to be 0.47, 0.55, 0.61, 0.69 and 0.77 for Phase 1 diets, and 0.47, 0.55, 0.63, 0.71 and 0.78 for Phase 2 diets. Following infection, oedema disease was diagnosed in all groups including the non-infection control group, therefore data from non-infected pigs were combined with pigs infected and fed 0.55 SAA:Lys for analysis of production and plasma data. There were no dietary effects of SID SAA:Lys on days with diarrhoea or faecal shedding of F4 ETEC (P > 0.05). Overall, average daily gain (ADG), feed intake and G:F were optimised at 0.71 (SE = 0.073), 0.73 (SE = 0.065) and 0.68 (SE = 0.090) SID SAA:Lys, respectively. For pigs infected with ETEC and not provided with antimicrobial compounds, and under conditions of the current study, it is suggested that the SID SAA:Lys lies above the current NRC recommendation of 0.55 for pigs after weaning.