OBJECTIVE: The inhibitory potential and percent inhibition of Syzygiumaromaticum oil and fresh juice of Ocimumsanctum leaves on beta-lactamase enzyme of cecal samples of healthy broilers were studied on samples phenotypically positive for extended-spectrum beta-lactamase (ESBL)-producing Escherichiacoli.MATERIALS AND METHODS: Four hundred cecal samples screened for ESBL-producing E. coli were collected from 38 poultry sale outlets located in Jabalpur. The effect of S.aromaticumoiland O.sanctum leaves was seen by colorimetric assay with CENTA and Nitrocefin as chromogenic substrate.RESULTS: Mean absorbance value was inversely propotional to the inhibitory potential. Syzigium aromaticum exhibited 0.4±0.02 and 0.41±0.03 mean absorbance value, 28 per cent and 27 per cent of inhibition with CENTA and Nitrocefin respectively. Ocimum sanctum mean absorbance value and per cent inhibition with CENTA and Nitrocefin was 2.03±0.02 and 10.0 ; 1.97±0.06 and 10.0 respectively (p>0.05) showing non- significant difference in CENTA and Nitrocefin activity. Tazobactum (100 μM) as standard control exhibited a mean absorbance value of 0.12 ± 0.01 and 0.13 ± 0.01 and percent inhibition of 99.88 and 98 against CENTA and Nitrocefin, respectively. Combination of Ocimum sanctum and Syzigium aromaticum showed range of 1.69±0.05 to 1.90±0.08 1.61±0.06 to 1.92±0.08 of absorbance value with per cent inhibition of 14 to 15.9 with CENTA and Nitrocefin respectively.CONCLUSION: The results depicted that the inhibition of beta-lactamase enzyme activity with S.aromaticum oil was higher than that of O.sanctum leaf juice, and combination of both the herbs showed not much difference in activity.