When fibrinogen solution is incubated at low temperature, it converts to gel state spontaneously without the action of thrombin. The fibrinogen gel induced by low temperature is called “cryogel” and is associated with various diseases such as thromboembolic disorders, Raynaud’s disease and rheumatoid arthritis. In our previous paper, we have reported that cryogelation is inhibited by the addition of glucose and/or mannose. In this study, the additive effects of betaines on the cryogelation were examined. Betaines are known as the mild solubilization agents that prevent protein aggregation. Betaines used in this study are glycine betaine, non-detergent sulfobetaine (NDSB) -195 and Choline-O-Sulfate (COS) which is similar to NDSB-195. Bovine fibrinogen was dissolved in a phosphate buffer saline solution at the concentration of 3 mg/ml. Respective betaine was added to the fibrinogen solution at various concentrations, and turbidity measurements of those solutions were carried out over the wavelength range of 350 to 800 nm at 2°C. The characteristic quantities to the fiber structure composing the cryogel network (mass/length ratio, radius and density of the fibers) were analyzed according to the procedure employed by Carr et al. Fibrinogen cryogelation was inhibited by the addition of the betaines. Among the betaines used in this study, the order of inhibiting effect on the cryogelation was in the order of COS > NDSB-195 > glycine betaine. Fibrinogen in the presence of COS or NDSB-195 formed loose fibers with low density.