Acute schistosomiasis (Katayama fever) may present with a broad spectrum of symptoms three to six weeks after primary infection by Schistosoma (S) mansoni, S. japonicum or, more rarely, S. haematobium. The acute phase of schistosomiasis is frequently confused with other feverish diseases. It occurs almost exclusively in nonimmune visitors to endemic areas. We describe seven cases of acute S. mansoni infection. The pathogenesis, clinical features, diagnosis and treatment are briefly discussed. Katayama fever should be considered in patients returning from endemic areas with fever and eosinophilia. Clinically normal, but potentially exposed travel companions should be examined as well. Early diagnosis and treatment may be important in preventing the infection's serious sequelae of the infection.