This study examined the validity of trilingual test as a test accommodation to assess the Indigenous pupils' mathematical performance in Malaysia. The study employed two tests; BM-only test with items written in Malay language (BM) and trilingual test, which had items written in BM and English, and oral audio recording in their native Temiar Language. Each test had the same 30 computation and 20 word problem items, which measured the same mathematical content and skills. Using spiral administration, 33 Grade Five pupils sat for the BM-only test while 34 pupils sat for the trilingual test from two schools in one state. Rasch analysis was conducted using WINSTEP 3.72. The results indicated that both tests had comparable content and score. The trilingual test that used orally translated items in the Indigenous native language benefitted the Indigenous pupils in bilingual immersion programmes and was a valid measure of their mathematical ability.