This eight-week study was designed to determine the effects of Yaji and Yaji-additives on hematological parameters in adult Wister rats. The animal subjects were divided into five groups (A–E) and during the duration of study, group A (control) received 300g of growers mash (GM) only, while group B received 237g of GM plus 9g of each of the combined constituents of Yaji. Groups C, D and E received 291g of GM plus 9g of salt, monosodium glutamate (MSG) and groundnut powder respectively. At the end of each week, blood samples from 3 randomly selected rats were collected and analyzed. The first four weeks served as the acute treatment period (B1-E1), while both the first and second four-weeks (eight weeks) served as the chronic treatment period (B2-E2). The results showed that there was a significant reduction in the PCV of groups B1 and C2 (p<0.05) and in the WBC and monocyte counts of group C1 (p<0.05). However, no significant changes was observed in the PCV, WBC, and differentials of the other groups (p>0.05). It is our opinion therefore, that there is a need to control the quantities of the additives in Yaji considering the observed influence of salt in group C
