The introductory part has summarized the role of malaria in the course of history and various attempts of its eradication in Croatia before the World War I. Furthemore, there is a list of activities and results accomplished between 1922 and 1927 on the island of Krk by Dr. Otmar Trausmiller. After a systematic sanitation of all anopheles habitats, primarily natural and artificial bodies of still water, and introduction of imported gambusia to those bodies of water, anopheles was virtually eradicated on the island. What followed was an evident decrease of new malaria incidents, and in the campaign against malaria there was still major concern in the form of chronic patients and intensive quinine therapy. Today, about eighty years after it was introduced to Krk, gambusia still abides in ponds across the island and it represents one of the main factors in the protection against potential revival of indigenous malaria.