Llanfyllin High School (Welsh: Ysgol Uwchradd Llanfyllin) was a bilingual secondary school situated in the mid-Wales town of Llanfyllin. As of its final Estyn inspection in February 2016, it had 824 pupils, down from 1,001 in 2009.^[1]

Llanfyllin High School Ysgol Uwchradd Llanfyllin
Location
Llanfyllin , Powys Wales
Coordinates	52°45′50″N 3°16′19″W / 52.7638°N 3.2719°W / 52.7638; -3.2719
Information
Type	Secondary School
Closed	2020
Local authority	Powys County Council
Head teacher	Dewi Owen
Gender	Mixed
Age	11 to 18
Enrolment	824 (February 2016)[1]
Language	English / Welsh bilingual
Website	www.llanfyllin-hs.powys.sch.uk [dead link]

Around one fifth of its pupils lived across the English border in Shropshire, and 18% spoke Welsh as a first language as of 2016. Only one pupil was learning English as a foreign language. The proportion of pupils with special educational needs was lower than the national average, and 6% qualified for free school meals, compared to a national average of 17.4%.^[1]

As a bilingual school, Llanfyllin High School had a Welsh language stream in which most subjects were taught in Welsh, and an English language stream in which most subjects were taught in English. Some courses were taught bilingually.^{[2][non-primary source needed]} A group of pupils in years 6 to 9 participated in a project named Trochi (Immersion) to increase their fluency in Welsh and allow them to transfer to the Welsh language stream.^{[3][non-primary source needed]}

The school closed in 2020, merging with Llanfyllin Community Primary School to form an all-through school, Ysgol Llanfyllin.^[4]