A method for producing a polysaccharide and a conjugate vaccine including the polysaccharide produced according to the method. A characteristic step in the method is that the pH of the culture medium is kept at a constant value with base or acid until adjustment with respectively base or acid is not possible anymore. Using the method, capsular polysaccharide may be obtained in a high yield in a relatively short time. The method is straightforward, reproducible and cost-effective.