They produce more of it and it is of higher quality, suggesting they are better equipped to start a family than their intellectually inferior friends and colleagues, the study's researchers said.
To reach the conclusion, researchers from the Institute of Psychiatry at King's College London compared archived data on 425 Vietnam War veterans.
This dated back to 1985, when the men had given sperm samples as part of an extensive medical and undergone intelligence testing.
Comparing the two clearly showed that the brainiest men had the best quality sperm, reports the Telegraph.
Rosalind Arden, lead author, said "As an initial proof-of-concept, we took two characteristics that seemed, on the surface, unlikely to be associated with each other- intelligence and sperm quality - and tested whether there was a statistical relationship between them.
"We found a small positive relationship: brighter men had better sperm. But we are not trying to say that under modern conditions intelligent men are going to have more children. We wanted to test the idea that intelligence is favoured by natural selection."
The effect remained after factors, such as intelligent men being less likely to smoke and more likely to exercise more, were taken into account.
The research is published in the Journal Intelligence.
Dr Allan Pacey, Senior Lecturer in Andrology, University of Sheffield, said: "The fact that it's possible to detect a statistical relationship between intelligence and semen quality in adult men probably says more about the co-development of brain and testicles when the man was in his mother's womb, and therefore how well they both function in adult life, rather than suggesting that playing Sudoku can somehow stimulate more sperm to be produced.
"The improvement in semen quality with intelligence observed in this paper is small and therefore it is unlikely to have a big impact on the ability of men of different intelligences to conceive."
The effect was small so is unlikely to be relevant to individuals, Arden said.
During the analysis, the researchers examined the relationships between intelligence, semen quality which was measured using standard sperm motility, sperm concentration, sperm count tests, age, and the main lifestyle factors known to predict health: obesity body mass index, and use of alcohol, tobacco, marijuana, and hard drugs.