Just over 25% of secondary school children across the Shannonside region were absent for more than 20 days in 2021.
The figures from the Central Statistics Office show that Longford had the highest rate of absenteeism at 32.9%.
This is followed by Roscommon at 25.8% and Leitrim at 18.9%.
The findings show a jump in absenteeism of more than 20 days from pre-pandemic figures with Roscommon jumping from 15% in 2020 to 25.8% in 2021.
Nationally, 28% of students were absent for more than 20 days in 2021, a significant increase on the previous year's figure of 17%.