Abstract: A method for arithmetic decoding improves the reliability of the arithmetic coding. For the purpose of channel decoding, use is made of a soft output Viterbi algorithm which, along-side the decided data item, supplies an item of reliability information. In addition, a data item is predicted for the decided data item in accordance with channel-decoded and arithmetically decoded data already transmitted, and subsequently arithmetically coded and compared with the channel-decoded data item. If the two data items do not correspond, the distribution density function used for the arithmetic decoding is changed by using the reliability information, and the channel-decoded data item is subsequently arithmetically decoded using the new distribution density function.