Malaysian herbs such as curry leaves (Murraya koenigii), kaffir lime leaves (Citrus hystrix), pandan leaves ( Pandanus amaryllifolius) and turmeric leaves (Curcuma longa) are often used as flavourings in Malaysian food. They may contain various phytochemicals, which may act as antioxidants or pro-oxidants. In order to investigate the antioxidant capacity, the extracts of these herbs were subjected to antioxidant tests and analysed for polyphenol content. For the accelerated oxidation study, the ethanolic extracts were added to refined, bleached and deodorized (RBD) palm olein and heated to 180°C for 32 hr. The polyphenol content was observed to be highest in turmeric leaves (116.3 mg g^-1 gallic acid equivalents), followed by curry leaves (109.5 mg g^-1), kaffir lime leaves (103.2 mg g^-1) and pandan leaves (101.8 mg g^-1). In the DPPH assay and the linoleic acid model system, the antioxidative activity was highest in turmeric leaves followed by curry leaves, kaffir lime leaves and pandan leaves. However, in heated oil, the highest activity was observed in the sample containing curry leaf and kaffir lime leaf extracts at 0.4% with activities comparable to that of BHT (p<0.05). Based on the oxidative stability index (OSI), each of the herbs was capable of retarding oxidation significantly even at 0.1% compared to BHT (p<0.05). The results of this study suggest that these Malaysian herbs have great potential as heat-stable antioxidants, and could be used as alternatives to existing synthetic antioxidants.