Objective To optimize mixing ratio of gadolinium and iopromide contrast agents for MR hysterosalpingography(MR-HSG).Methods Sixteen kinds of mixed contrast agents including gadolinium and iopromide,i.e.saline contrast agent(GD-NS),gadolinium and iopromide contrast agent(GD-I370)and gadolinium and iodixanol contrast agent(GD-I320)were prepared and scanned using 1.5T and 3.0T MR scanners,respectively.Imaging quality was subjectively assessed,and the signal intensities(SI)were compared among different contrast agents and between 1.5T and 3.0T.Taken the mixing ratio resulted the highest SI as the optimal mix ratio,MR-HSG was performed in 2 cases.Results For 1.5T scanning,1∶80 was the best ratio of GD-NS,1∶300 was the best for both GD-I370 and GD-I320,while no significant difference of SI was found among GD-NS,GD-I370 and GD-I320(P＞0.05).For 3.0T scanning,1∶50 was the best ratio of GD-NS,while 1∶200 was the best for both GD-I370 and GD-I320.Significant differences of SI were found among different contrast agents(P＜0.05),SI of GD-NS was higher than that of GD-I370 and GD-I320(both P＜0.05),while of the latter two were no significant different(P＞0.05).SI of GD-NS,GD-I370 and GD-I320 under 1.5T were all lower than that under 3.0T(all P＜0.05).MR-HSG clearly showed fallopian tubes using 1∶200 GD-I370 in 2 cases.Conclusion 1∶300 gadolinium-iodine mixed contrast agents were suitable for 1.5T MR-HSG,while 1∶200 gadolinium-iodine mixed contrast agent were suitable for 3.0T MR-HSG.