A process for the manufacture of chitosan from a naturally occurring chitin source comprises the following steps: (a) a naturally occurring chitin source is demineralized by immersing it in a demineralization ("DMIN") 0.5 to 2M hydrochloric acid solution at a temperature of 20° to 30° C and for a DMIN time period of 0.5 to 2 hours to demineralize the chitin source, and then separating the resulting demineralized chitin source from the acid solution, washing the chitin source in a DMIN wash water for a DMIN wash period of 0.5 to 2 hours to remove the hydrochloric acid and calcium salts therefrom, and then separating the demineralized chitin source from the DMIN wash water; (b) subjecting the demineralized chitin source to deproteination ("DPRO") by treating the demineralized chitin source in a DPRO sodium hydroxide solution containing from 1 % to 10% w/w NaOH for a DPRO time period of 4 to 24 hours and at a temperature of 60° C to 80°C to deproteinize the demineralized chitin source, and then separating the resulting demineralized and deproteinized chitin source from the deproteination sodium hydroxide solution, washing the separated demineralized and deproteinized chitin source in a DPRO wash water for a DPRO wash period of 0.5 to 2 hours to remove the sodium hydroxide from the demineralized and deproteinized chitin source, and then separating the demineralized and deproteinized chitin source from the deproteination wash water; (c) separating residual water from the chitin source obtained in step (b); (d) immersing the chitin source obtained from step (b) into a sodium hydroxide deacetylation ("DEAC") solution containing from 40% to 50% w/w NaOH and carrying out deacetylation at a temperature of 90°C to 110°C and for a DEAC time period sufficient to convert acetyl groups of the chitin source obtained from step (c) to amine groups, to thereby form a chitosan biopolymer having d -glucosamine as the monomer of the chitin biopolymer, then separating the resulting chitosan biopolymer from the DEAC solution and washing the separated chitosan biopolymer in a DEAC wash water for a DEAC wash period of 1 to 3 hours to remove sodium hydroxide from the chitosan polymer, and then separating the chitosan biopolymer from the DEAC wash water; and (e) residual water is then separated from the chitosan biopolymer which is then dried in air at a temperature of from 50° C to 65°C for a drying time of 2 to 5 hours to reduce the moisture content of the chitosan biopolymer to below about 10% by weight to provide a medical-grade quality chitosan. (a) a naturally occurring chitin source is demineralized by immersing it in a demineralization ("DMIN") 0.5 to 2M hydrochloric acid solution at a temperature of 20° to 30° C and for a DMIN time period of 0.5 to 2 hours to demineralize the chitin source, and then separating the resulting demineralized chitin source from the acid solution, washing the chitin source in a DMIN wash water for a DMIN wash period of 0.5 to 2 hours to remove the hydrochloric acid and calcium salts therefrom, and then separating the demineralized chitin source from the DMIN wash water; (b) subjecting the demineralized chitin source to deproteination ("DPRO") by treating the demineralized chitin source in a DPRO sodium hydroxide solution containing from 1 % to 10% w/w NaOH for a DPRO time period of 4 to 24 hours and at a temperature of 60° C to 80°C to deproteinize the demineralized chitin source, and then separating the resulting demineralized and deproteinized chitin source from the deproteination sodium hydroxide solution, washing the separated demineralized and deproteinized chitin source in a DPRO wash water for a DPRO wash period of 0.5 to 2 hours to remove the sodium hydroxide from the demineralized and deproteinized chitin source, and then separating the demineralized and deproteinized chitin source from the deproteination wash water; (c) separating residual water from the chitin source obtained in step (b); (d) immersing the chitin source obtained from step (b) into a sodium hydroxide deacetylation ("DEAC") solution containing from 40% to 50% w/w NaOH and carrying out deacetylation at a temperature of 90°C to 110°C and for a DEAC time period sufficient to convert acetyl groups of the chitin source obtained from step (c) to amine groups, to thereby form a chitosan biopolymer having d -glucosamine as the monomer of the chitin biopolymer, then separating the resulting chitosan biopolymer from the DEAC solution and washing the separated chitosan biopolymer in a DEAC wash water for a DEAC wash period of 1 to 3 hours to remove sodium hydroxide from the chitosan polymer, and then separating the chitosan biopolymer from the DEAC wash water; and (e) residual water is then separated from the chitosan biopolymer which is then dried in air at a temperature of from 50° C to 65°C for a drying time of 2 to 5 hours to reduce the moisture content of the chitosan biopolymer to below about 10% by weight to provide a medical-grade quality chitosan.