New figures show 121,462 students travelled to Ireland from 121 countries last year to study English.
Marketing English in Ireland (MEI) said Brazil was the most popular country for students studying English.
Some 15,086 Brazilian students registered here during 2018.
Students were also remaining longer in Ireland, as the number of weeks they stayed in the country rose to 5.3%.
While European Union students stayed on average 2.4 weeks, students who require a visa stayed on average 20 weeks.
Students who do not require a visa stayed an average of 11 weeks.
However, the total number of students represents a decrease from 2017.
MEI is an association of English language schools in Ireland.
Its CEO David O'Grady said: "The opportunity to study in Ireland has many long term benefits for the student who can then progress with ambition towards their future career"
"That said we need to heed the dip in numbers recorded over 2018.
"With Brexit approaching we need to prepare ourselves for challenging times but also strategically plan to optimise the benefits of being the only English-speaking country left in the EU.
"The opportunity for Ireland to become the number one destination in Europe to study English is there but we need to ensure we remain competitive to ensure that we retain the numbers and grow them in time."