A team from Glasgow University tracked the health of more than 6,000 male volunteers over a period of 37 years.
They found men who drank over seven cups of tea per day had a 50% higher risk of developing prostate cancer than moderate and non tea drinkers.
The team said it did not know if tea was a risk factor or if drinkers lived to ages where cancer was more common.
Prostate cancer is the most common cancer amongst men in Scotland and diagnosed cases increased by 7.4% between 2000 and 2010.
The Midspan Collaborative study began in Scotland in 1970 and gathered data from 6,016 male volunteers all aged between 21 and 75.
Volunteers were asked to complete a questionnaire about their usual consumption of tea, coffee, alcohol, smoking habits and general health, and attended a screening examination.
Just under a quarter of the men included in the study were heavy tea drinkers.
Researchers found that men who drank more than seven cups of tea per day had a significantly increased risk of prostate cancer compared to those who drank no tea or less than four cups per day.