This study was aimed at determining the effects of the acetone extract of the Chromoleana odorata leaves on male fertility by evaluating some andrological and haematological parameters of the Wistar rat. A total of 20 sexually male Albino haematological Wistar rats were randomly divided into 4 groups. The rats in group A (Control) were administered with 1ml of distilled water, while rats in groups B, C, and D were administered with the extract of 100, 200 and 500 mg per Kg body weight, respectively, once daily for 28days. The result revealed that the rats in the control group (distilled water) result had significantly higher (p<0.05) sperm concentration (72.00 ± 2.83 + 106cell/ml) compared to group B (65.10 ± 2.63 + 106 cell/ml), group C (53.40 ± 3.45 + 10 6 cell/ml) and group D 42.75 ± 2.39 + 106 cell/ml treated with 500mg/kg with significant decrease in sperm concentration with increase in extract dosage. The rat in group A (control) had significantly higher (p<0.05) sperm viability percentage (96.45 ± 0.60) which when compared to group B which has the highest percentage, (92.43 ± 0.55), then a little decrease in group C (80.45 ± 3.75) and group D which has the lowest percentage (77.94 ± 2.56). The sperm motility at the control group (A) (98.53 ± 4.32) is high compared to the other group B, C and D, (95.48 ± 3.83), (83.73 ± 2.94), (75.75 ± 3.63) respectively. The pH value of the semen which vary from the control group (7.14 ± 0.16) to group B which is a little high (7.20 ± 0.13) and group C 7.19 ± 0.15, then group D which has the highest pH value 7.23 ± 0.17.There is significant increase in abnormal sperm morphology with the corresponding increase in the dosage of the extract compared across the groups. The results showed that there was a significant decrease (p<0.05) in the levels of Packed cell volume (PCV), Haemoglobin (Hb),white blood cell(WBC), red blood cell(RBC), Mean Corpuscular Haemoglobin Concentration (MCHC), lymphocyte, monocytes, platelets and eosino