As with other poultry diseases, many molecular methods are used for diagnosis of etiological factors in enteric diseases of birds. For detection of chicken and turkey astroviruses, RT-PCR-based methods have been developed that target conserved regions of ORFs1b and ORF2, which encode the viral polymerase and capsid protein, respectively [4, 5, 29, 30] . Because mixed infections with various types of astrovirus were identified in some cases, there was a need to distinguish between them. At first, the differentiation of four types of astroviruses, TAstV-1, TAstV-2, CAstV and ANV, relied on sequencing the amplicons. More recently, a new multiplex RT-PCR assay with primers specific for each of the four types of astroviruses was developed and used for survey of enteric viruses in the USA [5] . Overall, this method was unsuitable for differentiation of Polish isolates of astrovirus. Some isolates had additional changes in their nt sequences that prevented correct identification of astrovirus types (e.g., in the ORF1b sequence of PL/TK/G085/08, targeted by the T1pol1F primer, next to the three degenerate nucleotides, there were three additional nt mismatches; in the ORF1b sequence of PL/TK/G145/08 targeted by the ANVpolF primer, next to the four degenerate nucleotides, there were two additional nt changes). On the other hand, the usefulness of the primer set developed by Tang et al. [29] for detection of astrovirus seems to have been confirmed, as it was possible to detect astroviruses with many sequence variations. The presence of astrovirus in 44.15% (34/77) of Polish turkey flocks studied during 2008 is reported. The most frequently identified was TAstV-2, with samples positive from 30 of 77 flocks (38.9%), either as single or mixed infections. TAstV-1 was detected in only nine flocks, either as single or mixed infections (11.6) . ANV was detected in one flock (1.29%). These figures indicate that the prevalence of TAstVs in Poland was lower when compared with a prevalence of 84% reported in commercial turkey flocks during a survey in Minnesota, USA, during 2007-2008 by Jindal et al., or of 59%, reported in the UK; however, the prevalence in Poland was comparable to reports from Brazil (41.1%), as reported by Villarreal et al. [9, 12, 32] . However, it should be noted that in all the previous studies, astrovirus detection was focused only on the TAstV-2 type.