Malaria is endemic in the Indian state of Assam and transmission of the causative parasites is perennial and persistent. The available data on malaria-related morbidity and mortality in the state for the years 1991-1999 have been reviewed. Over this period, Plasmodium falciparum was the predominant parasite, causing 58%-68% of the malaria cases; all other cases were attributed to P. vivax. All malaria-related deaths were attributed to P. falciparum infection, and the numbers of such deaths were correlated with the numbers of cases of P. falciparum malaria. The deaths occurred mostly in the rainy season (April-September) and among all age-groups of both sexes. The factors responsible for focal outbreaks of malaria across the state are discussed in relation to the existing health infrastructure.