Ohlmarks translated the Sagan om Ringen, Sagan om de två tornen and the Sagan om konungens återkomst. They were considered very bad by Tolkien, who expresses a strong dislike in Letters 228 and 229. He wrote Guide to the Names in The Lord of the Rings to prevent further wrongdoing in translations. See also the link, "Lord of the Errors", below. The translation incorporated badly translated names, injection of adjectives and adverbs, and a very archaic and poetic style. Above all else, there are many errors based on insufficient knowledge of English - surprising, for someone who had translated famous works in other tongues, such the Quran and Dante.
Ohlmarks did not listen to the criticisms, and dismissed most of it. He became enraged when, in the 1970's, Christopher Tolkien wrote that he would only allow a Swedish translation of The Silmarillion if Ohlmarks was not connected to it.
Ohlmarks lost touch with Tolkien's world and, one could say, sanity. Two years before his death, he blamed Swedish Tolkien fans for a fire to his house, and wrote Tolkien och den svarta magin, "Tolkien and the Black Magic". In it, he concocted a conspiracy theory that claimed Tolkien, and the Tolkien Society, practised black magic and Nazi occultism.
In 2004, a new translation of The Lord of the Rings, made by Erik Andersson, was published in Sweden.