Prepared by the alkaline deacetylation of chitin obtained from the shells of shrimp (Pandalus borealis). Chitin is manufactured industrially by crushing shrimp shells, then washing the solids with acids to remove inorganic and proteinaceous material. The purified chitin is deacetylated to chitosan by treatment with a strong base such as sodium hydroxide. The resulting chitosan may be further purified by preparation of solutions in acid followed by neutralization and precipitation.