This study was conducted to verify the SID Lysine requirement of pigs fed Paylean (PLN) for 21 d, using carcass growth and G:F ratio as primary criteria.  A second objective was to verify previous work from our Lab that whole-body growth (WB) was promoted equally by low and high dietary SBM levels while carcass growth (Carc) was constrained by high SBM content.  A total of 420 Camborough x TR-4 castrates (216.7 ± 8.3 lbs) were allotted to diet in a 4 x 2 factorial arrangement (48 pens, 6 pens/diet).  Four SID Lysine levels were prepared (0.65, 0.75, 0.85, 0.95% SID) by summit blend; each having 5 PPM PLN.  Diets were formulated with only (a) SBM (H-SBM) or (b) reduced SBM (L-SBM) plus lysine, threonine.  Pigs were unexpectedly infected with diseases that trigger systemic inflammation.  Diagnostic results confirmed pigs as PRRS and PCV2 (circovirus) positive; PCV2 tissue lesions were present. Mortality and morbidity was 6 times normal (12.7%) for 16 weeks.  The inflammatory nature of these viruses is evident from the presence of circulating pro-inflammatory cytokines (J.Vet.Med.B Infec.Dis.Vet.Pub.Health 2006 Dec. 53 (10):488-93).  The main effect of SID Lysine was not significant (P>0.25) for WB ADG or G:F, however, the effect of SBM level was (P<0.05).  H-SBM pigs grew faster (2.18 vs 1.99 +0.06 lbs/d, WB), were more efficient (2.74 vs 2.87 +0.08, WB) and had greater Carc gain (31.4 vs 27.9 lbs).  The advantage of H-SBM, under conditions of high immune stress, was observed for Carc ADG and G:F (+12.8, +9.7% respectively).  The beneficial effect of H-SBM was evident at each Lysine level for WB ADG and G:F (SBM x Lysine, P>0.10).  Carcass yield was low but similar for SBM level (P>0.90, 74.7%), which is contrary to our results with healthy pigs.  The SID Lysine requirement (G:F) for the H-SBM regimen was 0.95%, using WB and Carc G:F.  This estimate is lower for pigs fed L-SBM diets (0.85%).  Some component of SBM appears to modify the impact of high immune stress on G:F ratio and the SID Lysine requirement.  We conclude that H-SBM level reduces the negative effect of inflammatory disease on ADG and G:F to a significant extent.  The mechanism is unclear but the anti-inflammatory SBM isoflavones may be involved.