Abstract： Objective To study the effects of the antiarrhythmic drugs of propafenone, amiodarone and dilthiazem on c-type Kv1. 4 channels in Xenopus laevis oocytes with two-electrode voltage-clamp technique. Methods Defolliculated oocytes ( stage Ⅴ - Ⅵ) had transcribed cRNAs of ferret Kv1. 4△N channels injected. The oocytes were continuously perfused with control solution or propafenone, amiodarone and dilthiazem under monitoring of software of Clampfit v 9. 0. Results All of the three drugs blocked ferret Kv1. 4△N channel in voltage-, frequency- and concentration-dependent manners. The values of IC50 (50%inhibiting concentration ) of propafenone, amiodarone and dilthiazem were ( 103.4± 2. 2 ) μ mol/L,(501.22 +5.9) μmol/L and (353.62 +9.9) μmol/L, respectively. The currents under the actions of propafenone , amiodarone and dilthiazem were decreased to 41%, 32% and 21% of control group, respectively. Propafenone (100μ mol/L), Amiodarone (500μmol/L), dilthiazem (350μmol/L) inhibited currents to (54. 6 + 1.9 ) %, ( 46. 3 + 3.5 ) %, ( 52. 8 ± 2. 8 ) % of control group in voltage-dependent blockage. Conclusions The results suggested that all the three drugs blocked the kv1. 4△N channel in the open state. The three drugs block the kv1. 4△N channel maybe had the similiar effects in some respects, but each had its unique characteristics.