Acetone extracts of cashew nut shell of Anacardium occidenatle, L. were investigated for their ability to inhibit 15 clinical isolates of methicillin resistant Staphylococcus aureus (MRSA) from patients of diabetic care centers. Antibacterial activity was determined for cashew nut shell liquid (CNSL) extract by finding minimum inhibitory concentration (MIC) using 96 well microtitre plates. A twofold serial dilution of compounds (100 μl) in sterile normal saline was prepared in 96-well microtitre plate and 50 μl overnight fresh bacterial cultures of one McFarland unit were added to each well. The plates were incubated overnight at 370C and bacterial growth was detected by adding and incubating for 30 min with 20 μl of p-iodonitrotetrazolium violet (INT) to each well. The well that remained color less when there was no bacterial growth and that concentration was taken as MIC. A negative control was also maintained in which all wells with bacterial growth in red color were found. MIC values(μg/mL) obtained for CNSL against 15 clinical isolates of MRSA were 0.00024 – 0.00375, Similarly the acetone extract of CNSL against MRSA (ATCC 33591) and for methicillin sensitive Staphylococcus aureus (MSSA) (ATCC 25923) MIC values for MRSA are 0.00024 μg/ml and for MSSA are 0.00375 μg/ml respectively. The strong in vitro antibacterial activity of the separated compound against MRSA suggests the wide pharmaceutical applications.