Background The study focused on the toxicological evaluation of leaf extracts of S. glauca on some hematological indices of male Wistar rats. Methods Thirty (30) male Wistar rats were divided into ten groups of three rats each. Test rats were given AESG, EESG or MESG at doses of 500, 1000 and 2000 mg/kg body weight respectively; the control group was provided with food and water ad libitum daily for thirty (30) days. At the end of the study, the fasted rats were sacrificed and haematological assessment was conducted. Results The data obtained indicates elevated (P ˂ 0.05) RBC levels of experimental rat administered EESG and MESG at 500, 1000 and 2000 mg respectively. Reduced (P ˂ 0.05) haemoglobin concentration at AESG and MESG 500 mg, AESG, EESG and MESG 1000 mg; EESG 2000 mg. The haematocrit/PCV levels where only slightly reduced (P ˂ 0.05) and elevated (P ˂ 0.05) at EESG 1000 and 2000 mg respectively. Platelets count was elevated (P ˂ 0.05) at MESG 500 mg, lowered at AESG 1000 mg and EESG 2000 mg. The WBC count was elevated (P ˂ 0.05) at AESG and EESG 1000 mg; elevated (P ˂ 0.05) at EESG and MESG 2000 mg. The lymphocytes count was elevated (P ˂ 0.05) at EESG 500, 1000 & 2000 mg; at AESG 1000 mg. The monocytes count was elevated (P ˂ 0.05) at AESG 500, 1000 & 2000 mg, elevated (P ˂ 0.05) AESG and EESG 1000 & 2000 mg respectively, and elevated (P ˂ 0.05) at MESG 2000 mg. Conclusion Oral administration of leaf extracts of S. glauca, especially at higher doses elicit disturbances in haematological indices.