Klaasen played four Tests for South Africa from 2019-2023.
The 32-year-old featured in four Tests for the Proteas, the last of which came against West Indies in March last year.
Klaasen is the second big-name player from South Africa to call time on Test cricket, after Dean Elgar. Elgar retired after the recent India Test series at home, and Klaasen was not part of that squad, after being dropped for Kyle Verreynne, but Test coach Shukri Conrad said Klaasen was still part of his plans.
Having spent quite a lot of his time in the South Africa Test team as an understudy to Quinton de Kock. He finally made his Test debut in 2019 on the tour of India, playing his first Test in Ranchi.
His second cap came after almost four years when he played in Sydney, Centurion, and Johannesburg in 2023. In all, he managed to total just 104 runs with a best of 35 and was since replaced in the XI by Kyle Verreynne.
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This retirement frees Klaasen from red-ball responsibilities and has him focus on the white-ball game after enjoying a very prolific 2023 in which he struck at 172.71 in T20s and 140.66 in ODI cricket.
"After a few sleepless nights wondering if I am making the right decision, I have decided to retire from red-ball cricket. It's a difficult decision that I have made because it is by far my favorite format of the game. The battles that I faced on and off the field have made me the cricketer I am today. It has been a great journey and I am glad I could have represented my country. My baggy Test cap is the most precious cap I have ever been handed,” Klaasen was quoted by Cricbuzz.
South Africa will play seven more Tests in 2024 - two each in West Indies and Bangladesh, two at home against Sri Lanka, and one against Pakistan. But they do not have any more home Tests between January 2025 and September 2026. They will only play in two-match series for the 2023-2025 World Test Championship cycle.