Background: Benign prostatic hyperplasia (BPH) is the most prevalent disease of the prostate in elderly men. Since Nigella sativa has been reported to show various pharmacological effects, this study was conducted to examine the effect of N. sativa seed oil on experimental BPH. Methods: The oil was extracted using the cold-pressing method. Fifty rats were divided into five groups of 10 each as follows: Group 1 orally (p.o.) received normal saline; groups 2e5 were castrated and subcutaneously received 5 mg/kg testosterone propionate for four weeks. Group 2, namely, BPH model, underwent no further treatment, Groups 3 and 4 were treated with 400 mg/kg and 800 mg/kg N. sativa seed oil, Group 5 received finasteride (0.5 mg/kg, p.o.) for 28 days. All groups received repeated testosterone injections for the following four weeks after BPH induction. After the treatments, rats were sacrificed and the prostate tissues removed. Wet weight, prostatic volume (PV) and prostatic index (PI) were determined. Serum prostate-specific antigen (PSA), dihydrotestosterone (DHT), malondialdehyde (MDA) and antioxidant levels were determined. Results: Our results showed that oral treatment with 400 and 800 mg/kg N. sativa oil led to a significant decrease in PI, PV, DHT concentration, PSA, and serum MDA level, and also significantly increased serum antioxidant capacity. Conclusions: The study demonstrated that the oil seed exerted anti-BPH effects which may be associated with its antioxidant properties in vivo
