Fusarium mycotoxins, namely deoxynivalenol, can negatively impact the nutritional quality of grains. This study evaluated the effects of feeding three naturally contaminated Fusarium-downgraded wheat sources on immunological parameters in broiler chickens. Sources were individually sorted into three fractions: outlier, high mycotoxin, and low mycotoxin, then reconstituted into four diet ratios in proportion to the high-mycotoxin fraction, providing a 3 × 4 factorial design. Immunological assessments were done by evaluating (1) cell-mediated responses to the mitogen phytohemagglutinin (PHA) through intermediate interdigital web swelling, (2) humoral responses to bovine serum albumin (BSA) antigen through induced antibody production, and (3) the heterophil to lymphocyte (H:L) ratio. Relative tissue weights and histopathology of selected immune tissues were assessed. Results indicate no significant differences (P < 0.05) in swelling response to PHA, secondary antibody response to BSA, or the ratio of heterophils to lymphocytes with increasing inclusion of high-mycotoxin fraction. Significant differences in relative tissue weights were only observed in spleen (P < 0.05) at 21 d and the liver (P < 0.01) at 35 d. Histopathology showed increases in lesions as lymphoid aggregates or granulopoisis in more contaminated diets. These results indicate broiler immune competence was not impacted with increasing mycotoxin exposure.