Abstract: Objective: To compare the performance of three kinds of microcolumn gel Coombs' test cards (BioXun, DiaMed and BioVue) in detecting titration of IgG antibody against blood group in pregnant women with blood type O and calculate their critical titres respectively. Methods: Parallel tests using three kinds of microcolumn gel Coombs' test cards and tube Coombs' test were carried out for detecting titration of IgG anti-A or IgG anti-B in 137 pregnant women whose blood types were O and incompatible to that of their husbands. Results: The mean titres of IgG anti-A(B) determined by BioXun,DiaMed and BioVue cards were 56.36(30.76),111.94 (59.02) and 104.47(58.08),respectively,and that determined by test tube Coombs' test was 28.31(16.41). The differences between mean titres which obtained using three kinds of Coombs' cards and which by test tube Coombs' test were significant(P < 0.01). The results of three kinds of Combs' tests were positively correlated with the results of tube Coombs' test(r=0.950,0.938; r=0.913, 0.901; r=0.873,0.883). The results between DiaMed cards and BioVue cards did not show any significant difference(P > 0.05). The differences between BioXun cards and DiaMed or BioVue cards were significant(P < 0.01),but the resuts of BioXun cards were highly correlated with each of them(r=0.960, 0.917; r=0.948, 0.940). Based on regression equations,the critical titres for IgG antibody against blood group IgG anti-A or IgG anti-B in pregnant women using BioXun,DiaMed and BioVue cards were 122(122),267(228) and 215(229), respectively. Conclusions: The three kinds of Coombs'cards are all hypersensitive,need to be redefined their critical titres. The sensitivity of domestic BioXun cards is lower than imported DiaMed or BioVue cards,but it has highly positive correlation with imported cards. The sensitivity of DiaMed and BioVue cards are at the same degree.