abstract the essential oil of eaglewood tree (aquilaria agallocha roxb.) has been considered to be a pathological product. an investigation was carried out to study the difference in composition of oils obtained from healthy, naturally infected and artificially inoculated eaglewood using gc and gc/ms analyses. this investigation showed a marked difference in the oil compositions among the treatments with regards to their quality. valerianol (3.0%) and tetradec-anioc acid (7.1%) contents were recorded higher in the oils of naturally infected plants than in that of healthy ones (0.1% and 6.9%, respectively). pentadecenoic acid was totally absent in the oils of healthy, whereas it was found in a greater amount (6.8%) in the oil of naturally infected plants. in contrast, dodecanoic acid (3.1%), pentadecanoic acid (6.2%), hexadecanoic acid (31.5%) and octadecanoic acid (4.1%) were found in a higher amount in the oils of healthy plants, while the oils obtained from naturally infected plants contained lower amounts of these components (2.5%, 4.8%, 20.0% and 1.0%, respectively). the oils obtained from the inoculated plants showed almost similar distribution of the components with healthy plants.