The present invention relates to a process for the production of structurally pure lactitol crystal forms selected from the group consisting of lactitol anhydride, lactitol monohydrate, lactitol dihydrate and lactitol trihydrate. The crystallization is performed by cooling a lactitol solution from a temperature at or slightly below the highest temperature of the stability area of the respective crystalline lactitol form to a temperature at or slightly above the lowest temperature of the stability area of said crystalline lactitol form, said stability areas being defined, respectively, within the temperature limits of 100 °C and 0 °C by the intersections of the solubility lines shown in Fig. 1, and by maintaining the supersaturation of said lactitol solution at a level of 1 to 8 % (w/w) above the solubility line of the respective lactitol form crystallizing in said area.