Abstract: The anti-microbial activity of methanol extracts of the leaves of Henna (20 and 40 mg mL^–1) was investigated against four pathogenic clinical isolates, namely; Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus using the agar well diffusion method. S. aureus was the most susceptible bacteria followed by Pseudomonas aeruginosa and Escherichia coli. While Klebsiella pneumoniae was the least susceptible micro-organism. The inhibition zone was correlated with the plant extract concentration. Chloramphincol (5 mg mL^–1) was used as standard anti-biotic. The MIC of the tested organisms at 40 mg mL^–1 of Henna leaves methanol extract were ranged between 2.5-20 mg mL^–1, correlated with the inhibition zones. The toxicological effects of aqueous suspensions of Henna administered to males of Wister albino rats were evaluated using 6 weeks (42 days) treatment. Mean body weights, hematological and biochemical analysis were evaluated. The treatment did not produce any mortality and no significant changes in body weight observed with doses 200 and 1000 mg/kg/day compared to the control group. Blood parameters showed no significant clinical changes either except some variations in mean counts of WBC, RBC and PLT. Biochemical parameters of rat’s serum revealed some significant differences. BUN, CRE, GLU and T. LIP for the test groups were in normal values and found statistically non-significant while ALT, AST, ALP, URIC, T. PROT and ALB were significantly decreased, particularly at dose 1000 mg/kg/day. Here, more investigations on sero-biochemical parameters are required. However, consumption of Henna leaves at least at level 200 mg/kg/day could be of no serious safety concern.