A new system for lectin-glycoprotein complexes dissociation constants (K) determination is presented. The system is based on agarose affinity electrophoresis where equal lectin (Con A) concentrations are inhibited by variable specific sugar (alpha-methyl-mannoside) amounts. Moreover, the system allows lectin-sugar inhibition constants (Ki) studies. For determination of mechanisms as well as K and Ki values calculations mathematical equations are developed. Values of K for two variants of alpha 1 acid-glycoprotein, two variants of alpha 1-antitrypsin, one variant of alphafetoprotein and Ki for Con A-alpha-MM are calculated according to the introduced equations and compared in a computed system. Moreover, the influence of sugar on lectin-glycoproteins interaction is demonstrated and discussed.