Central neurons in culture represent a limitless substratum for research in neurobiology and experimental neurology. Primary cultures of NIH mouse neurons have shown that about 83% of total cells in the cultures are neuron clumps, detected by their reaction with the neuron specific-enolase (NSE) marker. Herpes Simplex Virus type 1 (HSV-1) can grow efficiently in these cultures, as it does in nonneuronal cultures usually used for antiviral drugs testing. For that reason, the primary neuronal cultures were used for testing antiviral activity against HSV-1, after an overnight treatment with different concentrations of dsRNA from phi 6 bacteriophage. The dsRNA started to be toxic for the cells at concentrations of 4 micrograms/ml, but it was found that 1 microgram/ml of this dsRNA protected all the neuronal cultures from HSV-1 infection. The dsRNA value for effective dose (ED50) was 0.27 microgram/ml.