Abstract: The antimicrobial activities of p-menth-3-en-1-amine(1) and its Schiff base derivatives(2a-2l) against Staphylococcus aureus(gram-positive bacteria), Klebsiella pneumonia(gram-negative bacterium) and Candida albicans (fungus) were measured by using the microbroth dilution method. Then, the structure-activity relationship was established. The results showed that some products had certain antibacterial activities against these pathogenic bacteria. Compound 1 had the strongest antimicrobial activity against Staphylococcus aureus and the minimal inhibitory concentration(MIC) was 56.25 mg/L. Compound 2h and 2i had the strongest antimicrobial activity against Klebsiella pneumonia and the MICs were 112.5 mg/L. Compounds 2l had the strongest antimicrobial activities against Candida albicans and the MIC was 28.125 mg/L. The structure-activity relationship indicated that the antimicrobial activity would be stronger when the chlorine or bromine atom was introduced into the Schiff base derivatives; the antimicrobial activities of Schiff base derivatives containing a pyridine ring were higher than those of the Schiff base derivatives containing a furan, pyrrole or thiophene.