The rate has fallen from 74.5% in 2009/12 to 73.5% in 2010/13.
The Scottish Government described the decrease as "disappointing", although the results do exceed the minimum standard of more than 70%.
Scotland's breast screening programme is part of a UK-wide programme of free mammographic screening for breast cancer.
Under the programme, women aged 50-70 are invited to attend screening once every three years, which is why trends in performance can be measured in three-year rolling periods.
The latest figures, released by ISD Scotland, present the picture up to the end of March last year.
They show that the number of breast cancers detected by screening has increased from 1,164 in 2004/05 to 1,436 in 2012/13.
Of those detected in the latest period, over 80% were invasive, of which over half were less than 15mm in size.
The proportion of cancers for which diagnosis was confirmed pre-operatively has increased slightly from 97% in 2011/12 to 97.6% in 2012/13, a move which reduces the number of women requiring two operations.
The figures also show that all NHS boards except one achieved the target for more than 70% of those invited to a screening to go on and attend the appointment.
NHS Greater Glasgow and Clyde fell just short with an uptake rate of 68.8% in 2010-13. The mainland NHS board with the highest uptake rate for the same period was NHS Grampian at over 80%.
Health Secretary Alex Neil said: "The earlier cancer is detected, the easier it is to treat and more lives can be saved through early detection.
"While it is disappointing to see a slight decrease in uptake figures over the last three years, overall uptake of breast screening remains high and I would urge all women aged 50 to 70 to participate in the Scottish Breast Screening Programme.
"Breast screening plays a key role in increasing the early detection of cancer as it can pick up cancers that women would be unlikely to find themselves."