Abstract: Comparative evaluation of the effect of methanolic leaf extract from Spondias mombin was investigated in Swiss albino rats with induced multiple infections from Bacillus subtilis and Clostridium sporogenes. The rats were divided into four groups. The first group was given basal diet only. The second group was orogastrically dosed with standard inoculums of the test organisms. The third group was given standard inoculums of the organisms and treated with methanolic extract of Spondias mombin. The fourth group was given 10 mL of the extract only. Haematological analysis revealed an increase in total White Blood Count (WBC) values from 3200 to 3800 mm3 during infection. The Pack Cell Volume (PCV) was found to be in the normal range before infection but fall bellow the minimum value during active infection and normalcy restored after treatment of the infection with the plant extract. However, the neutrophil count in the infected rat was higher (42%) than in the control (40%). The amount of monocyte and eosinophil was not significantly different before infection and during infectivity whereas there was increase in the amount of lymphocyte in the infection stage which later got reduced after treatment with the extract. The urinalysis showed that the rats had pH of 6, negative to glucose, ketone, nitrite, ascorbic acid, protein, bilirubin, blood and positive urobilinogen for all groups before infection. The control rats showed a pH of 9, negative to glucose, ascorbic acid, ketone, nitrite, protein, bilirubin, blood and normal urobilinogen which showed the same pattern to all groups before infection. The methanolic extract of Spondias mombin has effect on the hematological parameters of the rats resulting from possible in vivo antimicrobial activity on the pathogens and thus justifies its use in ethnomedicine.