In most cases diagnosis of immediate-type occupational allergy is very complex. Mainly it is caused by diversity of occupational allergens and lack of standardized diagnostic methods. The content of allergic proteins in commercially available skin prick test reagents differs between companies and in some the most important allergens are not named. Also the evaluation of serum specific IgE (asIgE) is characterized by different diagnostic accuracy. In some cases, false-positive results of asIgE detection are the consequence of cross-reaction to common environmental allergens. In those cases it is helpful to determine asIgE for cross-reacting carbohydrate determinants (CCDs) to exclude cross-hypersensitivity. The presented paper reviews the structure of carbohydrate determinants, their prevalence and possible impact on laboratory in vitro tests used in allergy diagnostics, as well as the methods of their identification. Possible applications of CCDs in occupational allergy diagnostics are also discussed.