Anisotropic gelation has been studied by immersing chitosan in aqueous acetic acid sandwiched by a pair of square cover glasses into aqueous sodium hydroxide. The shape of the gel front line initially remained a square, whereas it approached a circle with immersion time. The time course of the distance between the side of the cover glasses and the gel front line xs was expressed initially as scaled proportional relationship (xs/L)2 =2K(t/L2), where t is the immersion time, L; the length of the side of the cover glasses and K; a constant. The characteristic behavior was independent of chitosan concentration.