A DNA extraction procedure was developed for the detection of ostreid herpesvirus-1 (OsHV-1) using the polymerase chain reaction (PCR) in oyster larvae. The DNA extraction procedure developed was tested on 8 larval samples. Abnormal nuclei with characteristic features associated with OsHV-1 infections were only observed in samples in which the viral DNA was detected by PCR. A previously described competitive PCR method was applied to detect inhibition during PCR reactions. The results show that the method can be used on small amounts of oyster larvae (3 mg) for the detection of OsHV-1 DNA by PCR.