Author has attempted to measure serial blood leucocyte and pseudoeosinophilic neutrophil counts to study the inter-relationships between blood total leucocyte levels and severity with prognostic significance of various craniocerebral injuries induced experimentally in rabbits. The experiments were performd on 31 rabbits of male sex, weighing between 1.5 and 1.7kg. On the degree of difference and severity of experimental injuries the animals were divided into the following 6 different groups;subarachnoid hemorrhage(Group I), local brain malacia(Group II), intracerebral hematoma(Group III), intraventricular hematoma(Group IV), unilateral carotid ligation(Group V), bilateral carotid ligation(Group VI). In each groups, total leucocyte and pseudoeosinophilic neutrophil counts were measured at times 1 hr., 3 hr., 6 hr., 12 hr., and 1, 2, 3, 4 day, respectively, after the injuries. The following results were obtained: 1. Mean levels of total leucocyte and pseudoeosinophilic neutrophil counts were 7263(193/mm3 and 35.1% in the control group. 2. The injured group, when compared to the control group of animals, had significantly raised total WBC and pseudoeosinophil counts at 3 hr. after the injuries, and the counts were returned to normal range at the third day after the injuries. 3. In each series of the unilateral carotid ligation, the raised total WBC and pseudoeosinophil counts did not differ significantly in the right ad left series each other. 4. Total WBC and pseudoeosinophil levels in the group of bilateral carotid ligation were progressively increased and the highest levels were seen between 6 hr. and 12 hr. after the injuries. 5. The most raised total WBC and pseudoeosinophil levels were seen in the group with bilateral carotid ligation and the next group was intraventricular hematoma, and the least raised group was subarachnoid hemorrhage. 6. It was concluded that the data showed highly significantly positive correlation between total WBC and pseudoeosinophil counts with the severity of injuries and its prognosis of craniocerebral injuries of rabbits induced experimentally. The greater increase in serial total WBC and pseudoeosinophil counts was seen in the group associated with higher degree of injuries, and the counts became to normal range at the third day with parallel to the degree of recovery after the injuries.