Abstract:The antibacterial activity of n-hexane extract of Ocimum gratissimum leaves was investigated against gram negative bacteria ( Salmonella typhi) and gram positive bacteria (Staphylococcus aureus ) . Agar well diffusion and broth dilution methods were employed. The results revealed that both first and second nhexane extracts (4days and 8 days n-hexane extract respectively) inhibited the microorganisms with the second being more active as it inhibited at 30mg/ml, 40mg/ml, 50mg/ml and 100mg/ml with zone of inhibition ranging from 8.5mm to 15.5mm in diameter. The first extract showed no inhibition at 30mg/ml and 40mg/ml respectively but showed inhibition at 50mg/ml and 100mg/ml with zone of inhibition ranging from 9mm to 12mm in diameter. The Minimum Inhibitory Concentration (MIC) of the second n-hexane extract ranged from 25mg/ml to 100mg/ml whereas, that for the first was at 100mg/ml. The result was compared to conventional drug (Gentamicin 20ug/ml)