Chapter 1 – Fundamentals of Testing
Pesticide Paradox – ISTQB Definition
Last Updated: July 12, 2026 · SoftwareTestPilot QA Team
Official ISTQB Definition
The phenomenon that if the same tests are repeated over and over again, eventually they no longer find any new defects.
In simple words
Running the same tests forever stops catching new bugs. You need to review and refresh test cases regularly.
Exam tip
The pesticide paradox is one of the seven testing principles and is a classic argument for updating regression suites.
Related terms
- Seven Testing PrinciplesSeven quick truths every tester should internalize — from ‘you can’t test everything’ to ‘no bugs found doesn’t mean the product is good enough’.
- Regression TestingAfter any change — bug fix, new feature, config update — you re-run existing tests to make sure nothing that used to work has broken.
- Defect ClusteringBugs are not spread evenly — a few risky modules host most of them, so focus extra testing there.
Practice this term in the ISTQB Mock Test
40 CTFL v4.0 questions, 60-minute timer, instant scoring and chapter-wise breakdown.
Practice in Mock Test