Almost 57,000 people over three years of age in the county stated that they could speak Irish in last year's census, down 3.8% on 2011.
Census 2016 found that just over 37% of people over the age of three in Donegal could speak Irish, slightly below the national figure of almost 40%.
7,931 people spoke Irish daily outside of the education system last year, down 13% on the 2011 figure.
The latest figure reflects 5.2% of the population aged 3 and over, compared with 1.7% at national level.
When Irish languauge usage in Gaeltacht towns and villages was assessed, Meenlaragh and Ranafast topped the league at 73% and 67% usage respectively, while an assessment of national trown over 10,000 population, Letterkenny was top, at almost 3% usage.
Statistics relating to education have also been published, with just over 33% of people over 15 saying they had a third level qualification. That's below the national average of 42%.
Females accounted for almost 61% of all graduates, with males comprising just over 39%.
Just over 18% had completed their education at lower secondary level and almosdt 27% at upper secondary level.
Almost 22% either completed their education at primary level or said they had no formal education.
Irish Language Statistics -