In this report, we described the extraction of L. donovani genomic DNA and construction of L. donovani genomic library in order to isolate individual gene and its products that can be the candidate to develop serum diagnostic and protective products for this disease. We prepared L. donovani promastigote genomic DNA using the protocols of extracting genomic DNA of cultivated cells by centrifugation (15,000 g, 60 min) to get rid of kinetoplast DNA. Genomic DNA was then partially digested with restriction enzymes Hae III, the digests were size-separated by gradient centrifugation, then ligated to EcoRI linkers, inserted to lambda gt11 arms, and packaged with pack gene in vitro. This procedure resulted in 2.28 x 10(6) phages and the insert proportion was 87%.