Scarlets U16s East produced an impressive display to see off Cardiff South 38-26 at Parc y Scarlets on Wednesday evening.
The sides were locked at 19-19 at half-time, but the home side pulled away strongly after the break to secure their first win of the campaign.
Scarlets tries were scored by hooker Toby Trickett, lock Sam Williams (two), wing Owen Gruffydd, skipper Keanu Evans and No. 8 Alex Ridgeway.
Fly-half Elis Price kicked three conversions and replacement Elis Payne another.
Scarlets West take on Ospreys West at The Gnoll in Neath on Thursday evening (7.15).