Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease involving both upper and lower motor neurons. Its underlying etiology is not well established. But certain risk factors including genetic predilection and exposure to certain environmental toxins like Organophosphorus Compounds (OPC) have been postulated. Here we describe a young male patient presented with progressive weakness of all four limbs immediately following survival from OPC ingestion as a suicidal attempt. He also had slurred, indistinct speech without swallowing difficulty and sensory findings. Neurological examination findings are having mixed upper and lower motor neuron signs. EMG (Electromyography) shows features of denervation and reinnervation suggestive of ALS. ALS following single exposure to OPC is a relatively rare finding. Supportive treatments including physiotherapy and psychotherapy were given. This case may strengthen the etiological link between OPC and ALS.