diff --git a/packages/casl-prisma/schema.prisma b/packages/casl-prisma/schema.prisma
index f4b41347a..d6354f56a 100644
--- a/packages/casl-prisma/schema.prisma
+++ b/packages/casl-prisma/schema.prisma
@@ -12,6 +12,7 @@ model User {
   firstName   String
   lastName    String
   age         Int
+  verified    Boolean?
   posts       Post[]
 }
 
diff --git a/packages/casl-prisma/spec/prismaQuery.spec.ts b/packages/casl-prisma/spec/prismaQuery.spec.ts
index dd13bd52b..ff39de61c 100644
--- a/packages/casl-prisma/spec/prismaQuery.spec.ts
+++ b/packages/casl-prisma/spec/prismaQuery.spec.ts
@@ -75,6 +75,22 @@ describe('PrismaQuery evaluation', () => {
       expect(test({ name: 'Jane Doe' })).toBe(false)
     })
   })
+  describe('isSet', () => {
+    it('throws if value is not a boolean', () => {
+      expect(() => prismaQuery({ items: { isSet: 1 } })).toThrow(/expects to receive a boolean/)
+      expect(() => prismaQuery({ items: { isSet: {} } })).toThrow(/expects to receive a boolean/)
+      expect(() => prismaQuery({ items: { isSet: true } })).not.toThrow()
+    })
+
+    it('checks that object value is not defined when using "isSet"', () => {
+      const test = prismaQuery({ verified: { isSet: true } })
+      expect(test({ verified: true })).toBe(true)
+      expect(test({ verified: false })).toBe(true)
+      expect(test({ verified: null })).toBe(true)
+      expect(test({ verified: undefined })).toBe(false)
+      expect(test({})).toBe(false)
+    })
+  })
 
   describe('in', () => {
     it('throws if passed value is not an array', () => {
diff --git a/packages/casl-prisma/src/prisma/PrismaQueryParser.ts b/packages/casl-prisma/src/prisma/PrismaQueryParser.ts
index f0d1c764b..4078bc59f 100644
--- a/packages/casl-prisma/src/prisma/PrismaQueryParser.ts
+++ b/packages/casl-prisma/src/prisma/PrismaQueryParser.ts
@@ -41,6 +41,15 @@ const not: FieldInstruction<unknown, ObjectQueryFieldParsingContext> = {
   }
 };
 
+const isSet: FieldInstruction<boolean> = {
+  type: 'field',
+  validate(instruction, value) {
+    if (typeof value !== 'boolean') {
+      throw ParsingQueryError.invalidArgument(instruction.name, value, 'a boolean');
+    }
+  }
+}
+
 const within: FieldInstruction<unknown[]> = {
   type: 'field',
   validate(instruction, value) {
@@ -195,6 +204,7 @@ const instructions = {
   none: inverted('some', relation),
   is: relation,
   isNot: inverted('is', relation),
+  isSet
 };
 
 export interface ParseOptions {
diff --git a/packages/casl-prisma/src/prisma/interpretPrismaQuery.ts b/packages/casl-prisma/src/prisma/interpretPrismaQuery.ts
index 930dda21f..0919acc1d 100644
--- a/packages/casl-prisma/src/prisma/interpretPrismaQuery.ts
+++ b/packages/casl-prisma/src/prisma/interpretPrismaQuery.ts
@@ -79,6 +79,11 @@ const not: JsInterpreter<CompoundCondition> = (condition, object, { interpret })
   return condition.value.every(subCondition => !interpret(subCondition, object));
 };
 
+const isSet: JsInterpreter<FieldCondition<Condition>> = (condition, object, { get }) => {
+  const item = get(object, condition.field);
+  return item !== undefined;
+}
+
 function toComparable(value: unknown) {
   return value && typeof value === 'object' ? value.valueOf() : value;
 }
@@ -112,6 +117,7 @@ export const interpretPrismaQuery = createJsInterpreter({
   every,
   some,
   is,
+  isSet,
 }, {
   get: (object, field) => object[field],
   compare: compareValues,