We have applied the temperature-dependent single-stranded conformational polymorphism (SSCP) analysis for characterization of influenza A virus cDNA fragments. A series of primers were synthesized on the basis of the comparison of hemagglutinin and PB2 gene sequences of different origin. RT-PCR reactions were run using these primers, products were denatured and single-strand DNA fragments were subjected to electrophoresis. After silver staining, ssDNA band patterns characteristic for each genotype were observed. Minor differences within a serotype were detected without need for sequencing the PCR products making the preliminary analysis of avian influenza isolates much faster.