The present study reports the prevalence of Whitespot syndrome virus (WSSV), Monodon baculovirus (MBV) and Hepatopancreatic parvovirus (HPV) in the Penaeus monodon post larvae in Tamil Nadu, Southeast coast of India. The PCR diagnosis of postlarvae revealed that 9.2% of the samples were infected with WSSV as they were positive either in one step or nested PCR. The PCR diagnosis of samples also showed that 9.6 and 6.4% of the samples screened were positive for MBV and HPV, respectively. Dual infection with MBV and HPV was observed by PCR in 2.6% of the samples screened. Multiple infection with WSSV, MBV and HPV was observed at 1.6% of the samples by PCR. Wet mount squash preparation from the hepatopancreas of postlarvae revealed that 5.5, 5.2 and 1.8% of the samples tested were positive for MBV, HPV and dual infection with MBV and HPV, respectively.