Commercial rainfed sugarcane cultivation in Papua New Guinea was begun in the early 1980s by Ramu Sugar Ltd. Over the last 15 years, annual cane yields have ranged from 28 to 88 tonnes/hectare, this wide variation being largely explained by sudden and catastrophic infestation by moth stem borers, cicadas, white grub and Ramu stunt virus. To a lesser extent yields were affected by weed competition, Changes in soil properties under continuous cultivation included decreases In pH, available phosphorus and exchangeable potassium, and some preliminary data suggest soil compaction. Leaf nutrient concentrations of nitrogen, phosphorus and potassium also declined slightly. It is concluded that yields were largely influenced by insect pests and diseases, but that the management of soil fertility is likely to become increasingly important once those problems have been solved.