Background: Celosia leptostachya belongs to Amaranthaceae plant family. Its leaves are used traditionally in the treatment of conditions, such as convulsion, eye infection and most notably to cure snakebites. This study investigated the inhibiting effect of the extract of C. leptostachya leaves against cobra snake venom in mice. Methods: We used 36 albino mice of mixed gender, weighing 20-25 g. They were divided into six groups of six rats each. Each rat was pre-treated with 0.4 mg/kg of cobra snake venom, and was subsequently given a graded dose of zero, 50, 100, 150, 200, or 250 mg/kg of the ethanol extract of C. leptostachya leaves. The animals were monitored for the survival rate. Various inhibition assays were performed to estimate the activities of acetyl cholinesterase, protease and adenosine triphosphatase of cobra venom, in the presence of 100-300 µg of the plant extract. Results: The extract inhibited the effects of cobra venom significantly after the intraperitoneal injection of the venom and extract at 20 minutes intervals. The results demonstrated that 100% of the mice survived if they received 100-250 mg/kg of the extract while only 83.3% survived with the extract at 50 mg/kg. The extract inhibited the venom’s acetyl cholinesterase, protease and adenosine triphosphatase. The inhibition occurred at higher percentages if the extract was given at 300 mg/kg. Conclusion: The plant extract significantly inhibited the snake venom, and its acetyl cholinesterase, protease and adenosine triphosphatase that mediated the venom’s toxicity.