Objective: To confirm the occurrence and describe the patterns of the 2003 malaria epidemics reported in the highlands of Ethiopia.

Design: A retrospective descriptive study.

Settings: Fifty epidemic affected districts between altitude ranges of 1500 and 2500 m in three regions in Ethiopia.

Results: Exaggerated seasonal transmission was observed in 25 districts, 16 in Oromia region and 9 in SNNPR. A sustained upward trend with 3-4 consecutive abnormal seasonal transmissions, which has started since 2002, has been identified in 22 districts. True explosive epidemic malaria was recorded at exceptionally high altitude (around 2500m) in at least one of the health facilities in seven districts. The incidence of malaria in 2003 epidemic has showed a six fold increase on average (range 2-20) from the threshold level.

Conclusion: Occurrence of a malaria epidemic was confirmed in all studied districts showing that the level of malaria endemicity and magnitude of the problem is increasing. The findings suggest the strategic importance of taking well-timed and appropriately targeted preventive and control interventions.