Among various kinds of documents, forms are the important types. The automatic processing of form documents is a problem which is essential to the advancement of office automation. The extraction of characters from form documents is a prerequisite for optical character recognition. In this paper, we will present a clustering-based technique for extracting characters from form documents. In this method, we treat the character extraction process as a pattern clustering problem. The feasibility of the novel method is demonstrated through experimenting various kinds of forms. Experimental results reveal the feasibility of the novel method.