A study was conducted to assess the effect of whole wheat (WW) feeding on performance, gizzard de- velopment, oocyst yield and intestinal lesion score of broilers challenged with Eimeria species. Diets (ground wheat (GW) and 300 g/kg WW replacing GW before or after pelleting) were offered ad libitum from day 1 or days 7–28 post-hatch. At 21 days of age, each dietary treatment was divided into two groups, one unchallenged control and the other inoculated with mixed species of coccidia (Eimeria acervulina, E. maxima and E. tenella). The results showed that heavier gizzards and higher mortality were observed in WW- fed birds in comparison to GW-fed birds. Interestingly, the pattern of mortality in different dietary treatments paralleled changes in gizzard size. Based on increased mortality, it is concluded that WW feeding exac- erbated the severity of coccidiosis infection, possibly via a mechanism involving enhanced gizzard development.