A study on 246 patients, reported in the journal European Urology, showed a single cycle of chemo was just as effective as the standard two cycles.
But the “shorter, kinder and cheaper” approach reduced the side-effects for cancer patients, scientists said.
Experts believe having less chemotherapy would make a “huge difference” to quality of life.
Testicular cancer is quite rare, affecting around 2,400 people in the UK each year.
However, it is unusual in that it strikes relatively young men – it is the most common type of cancer in those aged between 15 and 49.
The overwhelming majority of people diagnosed (98%) survive for at least 10 years after the cancer is first detected.
But as it affects people relatively young, the side-effects of treatment could last a lifetime.
The study, by the Institute of Cancer Research, London and University Hospitals Birmingham NHS Foundation Trust, was trying to reduce side-effects.