| MD | Players | Club | Nationality | DOB | A(D) |
|---|---|---|---|---|---|
| 08-Oct-2016 |  Matt Fagerson | Glasgow Warriors | Scotland | 16-Jul-1998 | 18(85) |
| 29-Oct-2016 | Keelan Giles | Ospreys | Wales | 29-Jan-1998 | 18(274) |
| 03-Feb-2017 |  Calvin Nash | Munster | Ireland | 08-Aug-1997 | 19(179) |
| 10-Sep-2016 |  Robert Lyttle | Ulster | Ireland | 28-Jan-1997 | 19(225) |
| 07-Oct-2016 |  Blair Kinghorn | Edinburgh Rugby | Scotland | 18-Jan-1997 | 19(262) |
| 23-Sep-2016 | Lewis Wynne | Glasgow Warriors | Scotland | 27-Nov-1996 | 19(300) |
| 03-Sep-2016 |  Josh Macleod | Scarlets | Wales | 27-Oct-1996 | 19(311) |
| 03-Sep-2016 | Jamie Ritchie | Edinburgh Rugby | Scotland | 16-Aug-1996 | 20(18) |
| 10-Feb-2017 | Scott Cummings | Glasgow Warriors | Scotland | 03-Dec-1996 | 20(69) |
| 25-Nov-2016 | Sam Underhill | Ospreys | England | 22-Jul-1996 | 20(126) |
| 26-Feb-2017 | Matthew Smith | Glasgow Warriors | Scotland | 05-Oct-1996 | 20(144) |
| 03-Dec-2016 | Harrison Keddie | Gwent Dragons | Wales | 10-Jul-1996 | 20(146) |
| 02-Sep-2016 | Jacob Stockdale | Ulster | Ireland | 03-Apr-1996 | 20(152) |
| 04-Mar-2017 |  Corey Domachowski | Cardiff Blues | Wales | 19-Sep-1996 | 20(166) |
| 03-Sep-2016 | Zander Fagerson | Glasgow Warriors | Scotland | 19-Jan-1996 | 20(228) |
| 26-Nov-2016 | Sam Arnold | Munster | Ireland | 08-Apr-1996 | 20(232) |
| 04-Nov-2016 | Murray McCallum | Edinburgh Rugby | Scotland | 16-Mar-1996 | 20(233) |
| 05-Nov-2016 |  Andrew Porter | Leinster | Ireland | 16-Jan-1996 | 20(294) |
| 02-Sep-2016 | Brett Herron | Ulster | England | 13-Nov-1995 | 20(294) |
| 29-Oct-2016 | Adam Beard | Ospreys | Wales | 07-Jan-1996 | 20(296) |
| 10-Sep-2016 | Kieran Treadwell | Ulster | England | 16-Nov-1995 | 20(299) |
| 26-Nov-2016 | Luca Sperandio | Benetton Treviso | Italy | 28-Jan-1996 | 20(303) |
| 02-Sep-2016 | Joey Carbery | Leinster | Ireland | 01-Nov-1995 | 20(306) |
| 10-Feb-2017 | Serafin Bordoli | Zebre | Italy | 15-Mar-1996 | 20(332) |
| 09-Sep-2016 | Tyler Morgan | Gwent Dragons | Wales | 11-Sep-1995 | 20(364) |
| 06-Jan-2017 | Daniel Jones | Scarlets | Wales | 07-Jan-1996 | 20(365) |
| 26-Feb-2017 | Dennis Bergamin | Zebre | Italy | 19-Feb-1996 | 21(8) |
| 02-Sep-2016 | Marco Lazzaroni | Benetton Treviso | Italy | 18-Aug-1995 | 21(16) |
| 09-Sep-2016 | Magnus Bradbury | Edinburgh Rugby | Scotland | 23-Aug-1995 | 21(18) |
| 30-Sep-2016 | Peter Robb | Connacht | Ireland | 19-Jul-1995 | 21(74) |
| 07-Oct-2016 | Garyn Smith | Cardiff Blues | Wales | 12-Jul-1995 | 21(88) |
| 03-Dec-2016 | Jeremy Loughman | Leinster | Ireland | 22-Jul-1995 | 21(135) |
| 03-Feb-2017 | Conor Oliver | Munster | Ireland | 21-Sep-1995 | 21(136) |
| 10-Feb-2017 | Luke Price | Ospreys | Wales | 26-Sep-1995 | 21(138) |
| 02-Sep-2016 | Ollie Griffiths | Gwent Dragons | Wales | 23-Mar-1995 | 21(164) |
| 02-Sep-2016 | Rory Thornton | Ospreys | Wales | 16-Mar-1995 | 21(171) |
| 17-Sep-2016 | Dafydd Howells | Ospreys | Wales | 22-Mar-1995 | 21(180) |
| 05-Nov-2016 | Ross Byrne | Leinster | Ireland | 08-Apr-1995 | 21(212) |
| 02-Sep-2016 | Gary Ringrose | Leinster | Ireland | 26-Jan-1995 | 21(220) |
| 03-Sep-2016 | Tomos Williams | Cardiff Blues | Wales | 01-Jan-1995 | 21(246) |
| 02-Sep-2016 | Jack Dixon | Gwent Dragons | Wales | 13-Dec-1994 | 21(264) |
| 03-Sep-2016 | Daniel Goggin | Munster | Ireland | 10-Dec-1994 | 21(268) |
| 03-Mar-2017 | Matteo Cornelli | Zebre | Italy | 06-Jun-1995 | 21(271) |
| 28-Oct-2016 | Ryan Elias | Scarlets | Wales | 07-Jan-1995 | 21(295) |
| 23-Sep-2016 | Ashton Hewitt | Gwent Dragons | Wales | 20-Nov-1994 | 21(308) |
| 01-Oct-2016 | Gideon Koegelenberg | Zebre | South Africa | 25-Nov-1994 | 21(311) |
| 28-Oct-2016 | Will Boyde | Scarlets | Wales | 15-Dec-1994 | 21(318) |
| 02-Sep-2016 | Ross Kane | Ulster | Ireland | 14-Oct-1994 | 21(324) |
| 29-Oct-2016 | Sean O'Brien | Connacht | Ireland | 09-Dec-1994 | 21(325) |
| 25-Nov-2016 | D'Arcy Rae | Glasgow Warriors | Scotland | 21-Dec-1994 | 21(340) |
MD = Match date,
DOB = Date of birth,
A(D) = Age(days).