Carmarthen Quins, newcomers to this stage of the Cup competition, will play Pontypridd at The Brewery Field on Saturday (2.30pm), with Cardiff and Llanelli taking up an old Cup rivalry at St Helens on Sunday (2.30pm).
Tickets for the matches are £10 for adults and £5 for OAPs and Under 16s. Tickets are available from the semi-finalist clubs or by calling WRU ticket office on 02920 822426 / garethd@wru.co.uk
The SWALEC Plate semi-finals will take place at Glynneath RFC where Maesteg take on Loughor, and Llanharan RFC where Kenfig Hill play Llantwit Fardre for a place in the Millennium Stadium final.
In the SWALEC Bowl, Senghennydd play Trebanos at Rhymney RFC and Abercarn play Pontardawe at Merthyr Tydfil RFC. All SWALEC Plate and Bowl semi-finals will take place at 2.30pm on Saturday 17 April.
Tickets for the those games are £5 for adults and £2 for children and OAPS and will be available on the gate on match day only.
All three SWALEC finals will take place at the Millennium Stadium on Saturday 8 May.