Long lists of psychiatric illness or symptoms have been documented to be caused 
by vitamin B12 deficiency. We describe an atypical case of a young adult who 
presented with predominant negative symptoms followed by neurological symptoms 
consistent with vitamin B12 deficiency. The symptoms showed complete remission 
after vitamin B12 supplementation. The uniqueness of this case is that vitamin 
B12 deficiency presented with predominant negative symptoms without other 
psychotic and manic symptoms, which has not been reported previously.