Combine peanut butter and pretzels in a small bowl and chill in the freezer until firm, about 15 minutes.
Roll the mixture into 20 balls (about one teaspoon each) and place on a baking sheet lined with parchment or wax paper until very firm, about one hour.
Melt chocolate in a microwave on medium for one minute. Stir, then continue microwaving, stirring every 20 seconds, until melted.
Dip the frozen balls into melted chocolate, set on wax paper and refrigerate until chocolate is set, about 30 minutes.