The majority of serum proteins are glycosylated. When disease is present, subtle changes occur in this glycosylation. These changes could provide the basis for more sensitive and more discriminative clinical tests. In order to address this possibility, a review is given of serum protein glycosylation in liver disease, inflammation and cancer. It is concluded that liver disease is accompanied by reduced sialylation and increased glycan branching; whereas cancer is accompanied by increased sialylation and increased fucosylation. In inflammation, the type of glycosylation change observed seems to depend upon the disease studied. Glycoprotein analysis can already be used for diagnosis in a few clinical situations; however, further studies are required in most diseases to provide a more detailed picture of the glycosylation changes that are occurring. This situation will change with the increasing availability of simpler techniques for glycoprotein analysis. One such group of techniques are lectin-based methods. The usefulness of these methods for glycoprotein analysis and the suitability for analysing clinical specimens are discussed in detail.