| 124 | EJG Morgan | Ireland Under-19s v New Zealand Under-19s | R Premadasa Stadium, Colombo | 2005/06 |
| 117 | EJG Morgan | Ireland Under-19s v Uganda Under-19s | MA Aziz Stadium, Chittagong | 2003/04 |
| 114 | PR Stirling | Ireland Under-19s v United States of America Under-19s | Queenstown Events Centre, Queenstown | 2009/10 |
| 101 | HT Tector | Ireland Under-19s v Namibia Under-19s | Lincoln No 3, Lincoln | 2017/18 |
| 95 | KJ O'Brien | Ireland Under-19s v West Indies Under-19s | Khulna Divisional Stadium, Khulna | 2003/04 |
| 91 | NA Rock | Ireland Under-19s v West Indies Under-19s | Bert Sutcliffe Oval, Lincoln | 2017/18 |
| 86 | EJG Morgan | Ireland Under-19s v Nepal Under-19s | Nondescripts Cricket Club Ground, Colombo | 2005/06 |
| 78 | TE Kane | Ireland Under-19s v Scotland Under-19s | WEP Harris Oval, Brisbane | 2012 |
| 77* | LJ Tucker | Ireland Under-19s v South Africa Under-19s | Sheikh Kamal International Cricket Stadium, Cox's Bazar | 2015/16 |
| 76 | AR White | Ireland Under-19s v Americas Under-19s | Radella Cricket Grounds, Radella | 1999/00 |
| 76 | AD Poynter | Ireland Under-19s v New Zealand Under-19s | R Premadasa Stadium, Colombo | 2005/06 |
| 75 | JD Hall | Ireland Under-19s v Bermuda Under-19s | Johor Cricket Academy Oval, Johor | 2007/08 |
| 75 | JB Grassi | Ireland Under-19s v Sri Lanka Under-19s | Cobham Oval, Whangarei | 2017/18 |