Plantation forestry, based on Eucalyptus species and clones, has been practised in the Republic of Congo since the early 1950s. A survey of plantations in the Pointe-Noire area undertaken in 1998 ldentified the diseases affecting plantation eucalypts. These in­cluded Cryphonectria canker, Botryosphaeria canker, Cylindro­cladium leaf blight and bacterial wilt. A new and serious disease of eucalypts, caused by Ceratocystis fimbriata, was reported for the first time during this survey. A number of secondary, opportunistic fungi were also isolated from diseased tissue. We believe that the impact of these diseases will increase in future, as clonai forestry is practised more extensively. Disease management programmes should thus be established to reduce losses.