There were 21,681 marriages recorded in Scotland between January and September, down from 24,053 in the same period the previous year.
The number of civil partnerships also fell over the first three quarters of the year, down 7% to 398.
Births decreased 3% to 42,283 over the same period, while a slight increase in deaths was recorded, up 0.9% to 41,047.
The annual number of deaths has fallen below 55,000 in recent years, compared to levels of around 60,000 to 65,000 from the mid-1940s to the mid-1990s.
The figures were revealed as the National Records of Scotland released provisional statistics for the third quarter of the year, covering July to September.
Chief executive Tim Ellis said: "Today's statistics show a fall in the number of deaths registered in Scotland, to the lowest number recorded in the third quarter for at least 40 years. However, taking the first three quarters of the year together, there were slightly more deaths than in the same period of 2012.
"The number of births also fell, continuing the trend of gradual decline since 2008. Levels of births and deaths are both relatively low in historical terms and since 2008 there have generally been more births than deaths.
"With an 11% fall in the number of marriages the quarter three total is at its lowest level for at least 40 years."