My wife and I plan to visit friends in Malaysia and take our five year old granddaughter with us. We have a letter from the parents sworn at the Ampur for us to take the child with us, so leaving Thailand isn't an issue. However does anyone know if we need a translation of the letter for Malaysian immigration?

I don't know the answer; but in your position would get one done anyway.

Better to have it and not need it than need it and not have it.

Indeed, that's my thinking too, the precautionary principle.

Well to answer my own question, no, the immigration official in Malaysia didn't request anything, didn't even ask a question, just stamped the passports. Though I did have a certified translation with me just in case.

Note that leaving Thailand the immigration officer requested a photocopy of the letter of authorisation, which I didn't have, however after he had talked to my granddaughter he was happy enough that she wasn't about to sold into slavery and was indeed just going for a three day trip to KL.