Inadequate disposition of petroleum based package materials has caused large environmental impact. Many researches have been developed trying to replace this materials by biodegradable products, been starch an alternative. In this study a biomaterial from modified starch, plasticizer and antimicrobial agent was obtained by extrusion and characterized, for biodegradable films making. Cassava starch varieties CUMBRE 3, SM 707-17 and CM 7138-7 were evaluated; thermal, mechanical and surface properties was obtained and optimum operating conditions for biomaterial obtaining. Additionally a microbial inhibition test was performed. When antimicrobial agent and plasticizer content were among 20% and 25% and among 0,1% and 0,2% respectively and extrusion processing temperature of 110 °C/120 °C/120 °C/110 °C, highest film strain stress were obtained (2,393 MPa). Tg films from CM 7138-7 variety in day 1 and day 21 then of obtained, had less variation. Antimicrobial test shows Fusarium fungus inhibition.