The present invention relates to a method for orientation-directed construction of a construct comprising at least two nucleic acid segments of interest. In a first step, products having phosphorylated blunt ends which have been derived from the nucleic acid segments of interest are provided. In a next step, separate ligation reactions are performed to combine two segments of interest. In each reaction, the phosphorylated blunt-ended products of two different segments obtained in the first step are ligated. This ligation creates a combined ligated sequence, comprising two segments of interest attached together. The next step is enrichment of the desired orientation in the resultant product population by performing a PCR reaction using the ligated sequence obtained in the second step, as a template and specific enrichment primers directing the PCR amplification towards the desired orientation. Each combined ligated sequence is PCR amplified in a separate reaction, to create combined product having the desired orientation as well as phosphorylated blunt ends. In a fourth step, the combined product obtained in the third step is isolated and purified. If the desired construct is composed of more than two segments, the second to fourth steps may be cyclically repeated for any desired number of times, to combine all the segments of interest. The final step is performing self-ligation of the linear final isolated purified combined product obtained in the former step, creating a circular double-stranded DNA construct containing all the desired segments properly aligned and operably linked in a desired orientation.