Abstract: A fragment of PCV2 BF strain with a size of 341 bp was amplified by PCR with a set of primer designed according to the genomic sequence of porcine circovirus type 2 available on GenBank. A nucleic acid probe labeled with digoxigenin-dUTP was prepared by random priming. The probe was not reactive to PCV1, porcine reproductive and respiratory syndrome virus (PRRSV), porcine parvovirus (PPV) and pseudorabies virus (PRV), and could detect 1.78 pg DNA of PCV2. Thirty clinical samples were detected with the developed in-situ Hybridization (ISH) and polymerase chain reaction (PCR). The results indicated that the ISH had a specificity of 100% and a sensitivity of 88.9%. Distribution of PCV2 in tissues of piglets inoculated with PCV2 was analyzed with ISH. The lymph nodes, thymus gland, tonsil, lung, spleen and nasal mucosa from the inoculated piglets exhibited positive signal at day 3 post-inoculation. The liver, kidney, pancreas and ileum were detected to be positive at day 21 post-inoculation. The heart, stomach and brain were positive at day 42 post-infection. The epiglottis cartilage, stomach, urinary bladder, skin, muscle and the tissues from un-inoculated piglets were negative during the experiment. The results suggested the in situ hybridization were sensitive and specific, and could be applied for clinical and laboratory detection of PCV2, as well as location of infected target cells of PCV2 .