| Inns | HS |
| 291-9 | 65 | Ireland Under-19s v Australia Under-19s | MA Aziz Stadium, Chittagong | 2003/04 |
| 278-8 | 91 | Ireland Under-19s v West Indies Under-19s | Bert Sutcliffe Oval, Lincoln | 2017/18 |
| 265-9 | 51 | Ireland Under-19s v Canada Under-19s | MA Aziz Stadium, Chittagong | 2003/04 |
| 259-9 | 95 | Ireland Under-19s v West Indies Under-19s | Khulna Divisional Stadium, Khulna | 2003/04 |
| 236-7 | 75 | Ireland Under-19s v Bermuda Under-19s | Johor Cricket Academy Oval, Johor | 2007/08 |
| 235-7 | 69 | Ireland Under-19s v Scotland Under-19s | Sheikh Kamal International Cricket Stadium, Cox's Bazar | 2015/16 |
| 225-8 | 37* | Ireland Under-19s v Afghanistan Under-19s | Cobham Oval, Whangarei | 2017/18 |
| 216-6 | 66 | Ireland Under-19s v South Africa Under-19s | Queenstown Events Centre, Queenstown | 2009/10 |
| 212 | 37 | Ireland Under-19s v Papua New Guinea Under-19s | Khulna Divisional Stadium, Khulna | 2003/04 |
| 212 | 56 | Ireland Under-19s v New Zealand Under-19s | Khan Shaheb Osman Ali Stadium, Fatullah | 2015/16 |
| 210 | 69 | Ireland Under-19s v England Under-19s | Colombo Cricket Club Ground, Colombo | 2005/06 |
| 207-8 | 75 | Ireland Under-19s v Sri Lanka Under-19s | Cobham Oval, Whangarei | 2017/18 |
| 201 | 70 | Ireland Under-19s v Bermuda Under-19s | Royal Selangor Club, Kuala Lumpur | 2007/08 |
| 191 | 47 | Ireland Under-19s v Kenya Under-19s | Gert Van Rensburg Stadium, Fochville | 1997/98 |
| 189 | 58 | Ireland Under-19s v India Under-19s | Shere Bangla National Stadium, Mirpur | 2015/16 |
| 185-8 | 47 | Ireland Under-19s v Nepal Under-19s | Endeavour Park, Townsville | 2012 |
| 185-7 | 77* | Ireland Under-19s v South Africa Under-19s | Sheikh Kamal International Cricket Stadium, Cox's Bazar | 2015/16 |
| 183 | 76 | Ireland Under-19s v Americas Under-19s | Radella Cricket Grounds, Radella | 1999/00 |
| 182 | 78 | Ireland Under-19s v Scotland Under-19s | WEP Harris Oval, Brisbane | 2012 |
| 177-9 | 34 | Ireland Under-19s v Australia Under-19s | Colombo Cricket Club Ground, Colombo | 1999/00 |
| 174 | 86 | Ireland Under-19s v Nepal Under-19s | Nondescripts Cricket Club Ground, Colombo | 2005/06 |
| 169 | 67* | Ireland Under-19s v Bangladesh Under-19s | Willowmoore Park Main Oval, Benoni | 1997/98 |
| 166-4 | 60* | Ireland Under-19s v Uganda Under-19s | Nondescripts Cricket Club Ground, Colombo | 2005/06 |
| 160 | 57 | Ireland Under-19s v Denmark Under-19s | Christian Brothers College Old Boys Ground, Boksburg | 1997/98 |
| 159-9 | 35 | Ireland Under-19s v Sri Lanka Under-19s | Christian Brothers School Ground, Boksburg | 1997/98 |
| 154-9 | 45 | Ireland Under-19s v West Indies Under-19s | Institute Perguruan Temenggong Ibrahim, Johor | 2007/08 |
| 153 | 21 | Ireland Under-19s v Pakistan Under-19s | Avion Park Cricket Club, Kempton Park | 1997/98 |
| 149-8 | 59 | Ireland Under-19s v Netherlands Under-19s | Radella Cricket Grounds, Radella | 1999/00 |
| 149 | 46 | Ireland Under-19s v Sri Lanka Under-19s | Allan Border Field, Brisbane | 2012 |
| 142 | 35* | Ireland Under-19s v Pakistan Under-19s | Khulna Divisional Stadium, Khulna | 2003/04 |
| 142-4 | 33 | Ireland Under-19s v Canada Under-19s | Sheikh Kamal International Cricket Stadium, Cox's Bazar | 2015/16 |