Abstract
1. Three strains of virus were isolated in suckling mice from the blood of three patients suffering from dengue during a local outbreak of the disease.2. One strain was adapted to adult mice and identified as a dengue virus of type 1. The identification was confirmed by workers in America.3. Evidence is presented that the other two strains of virus are similar to the one fully identified.4. Attention is drawn to the need for detailed work to find a more sensitive method of isolation for dengue viruses.