Abstract: The invention relates to a method for preparative production of long nucleic acids by PCR. The method involves the following hybridization steps: a) a nucleic acid base sequence is hybridized on the 3? and 5? ends with an adapter primer; b) the product from step a) is hybridized on the 3? and 5? ends with an extension primer containing an extension sequence, wherein a nucleic acid with extension sequences amplified and enlarged in the 3? and 5? ends of the nucleic acid base sequence is then formed from the nucleic acid base sequence. The invention also relates to different applications of the inventive method.