An experiment was conducted to determine whether pigs challenged with porcine reproductive and respiratory syndrome (PRRS) virus in a controlled environment benefit from inclusion of high levels of soybean meal (SBM) in the diet, as indicated in previous studies conducted on commercial farms. Sixty-four weaned pigs weighing about 6.5 kg and 21 days of age were used in a randomized complete block design, with two treatments (Low-SBM and High-SBM diets) and 32 replicates. Pigs were housed in individual pens in disease containment chambers for six weeks, two weeks before and four weeks after the intranasal inoculation. The pigs were phase-fed a series of three diets formulated to contain adequate amounts of energy and amino acids appropriate for their age. Initially, all pigs were fed the same diet. The SBM levels in the treatments were 12.5 and 19.5% for the Low-SBM treatment and 22.5% and 32.5% for the High-SBM treatment. Growth performance was measured weekly and rectal temperature on day 0, 3, 5, 7, 10, 12, 14, 17, 21 and 28 after challenge. Growth rates were similar to previous PRRS-challenged pigs. Dietary treatments did not affect ADG or ADFI, but G:F was greater on High-SBM during the first week post-inoculation and rectal temperatures were lower (P < 0.05) on days 3, 5 and 7 after challenge in pigs fed High-SBM compared to those pigs fed the Low-SBM treatment, suggesting a differential immune response. The researchers concluded that these data provide modest support for the previous indication that high levels of dietary SBM may benefit pigs infected with PRRS.