To study the individual and combined effects of fumonisin B₁ (FB₁) toxicity and Salmonella serotype Gallinarum infection, Japanese quail (Coturnix coturnix japonica) were fed Fusarium moniliforme culture material (2.5%), 150 mg FB₁/kg ration, and were subsequently challenged orally with Salmonella Gallinarum organisms (2 × 10⁴ colony-forming units) at 21 days of age. The chicks were fed culture material containing FB₁ from day 5 till the end of the experiment. After being infected with Salmonella Gallinarum, observations were made 1, 2, 3, 5, 7, 10, 14, and 21 days postinfection. The clinical signs of diarrhea with bloody discharges were more pronounced in the Salmonella-infected birds on the FB₁ diet. Mortality caused by Salmonella Gallinarum increased by 12% in the presence of FB₁. Mean body weights in both the Salmonella-infected and FB₁-fed groups were significantly lower than those of the controls at almost all intervals. Mean values of hemoglobin, packed cell volume, and total erythrocyte count were slightly higher in birds fed FB₁ but were lower in the Salmonella Gallinarum groups fed FB₁ and plain chick mash. Anemia was evident, between 5 and 10 days postinfection, in quail chicks infected with Salmonella Gallinarum alone. Total leukocyte counts were higher in Salmonella-infected and FB₁-fed groups because of an increase in the number of heterophils and lymphocytes. However, the increase in lymphocyte response to infection was lower by 4.27%–30.09% between 3 and 21 days postinfection in the FB₁-fed chicks compared with chicks infected with Salmonella Gallinarum. Alanine transaminase and total serum protein were slightly higher in both the infected and FB₁-fed groups. This study revealed that the continuous presence of fumonisins in the diets of quail chicks might increase the susceptibility to or the severity of Salmonella Gallinarum infection.