New figures show 55.6 per cent of those eligible for screening took up the offer between November 2015 and October 2017, below the target of 60 per cent.
Uptake for the test reached a high of 57.8 per cent between 2012 and 2014, and has been gradually decreasing since.
Those living in the poorest areas were less likely to take up the offer of a test, at 42.3 per cent compared to 65.3 per cent in the wealthiest areas.
All adults aged 50-74 are invited to take part in bowel screening every two years in Scotland, with those aged over 74 able to opt in.
The test remains the best way of finding bowel cancer early, when survival is 14 times more likely.
Of those who returned their screening kit, 2.1 per cent had a positive test result.
Three out of five screen detected cancers were diagnosed at the earliest two stages.
Gregor McNie, Cancer Research UK’s head of external affairs in Scotland, said a new test could be the answer to driving up participation.
He said: “Screening is important as it’s the best way to diagnose bowel cancer at an early stage when treatment is more likely to be effective.
“While these figures confirm that, in the last few years, the number of people in Scotland taking up the offer of bowel screening isn’t as high as we’d like to see, we hope this is about to change.
“A new test, called FIT, was introduced in Scotland in November. It’s likely that this will lead to more people returning the test as it’s easier to complete.”