Vitamin B12 deficiency has been implicated in various psychiatric conditions for a long time. The association could be primary, secondary to the psychiatric disorder, or even just coincidental. However, left untreated, the deficiency can delay or preclude recovery. Hence early recognition is important, especially when the traditional manifestations of B12 deficiency like anaemia, macrocytosis or spinal cord symptoms are not prominent. Three cases are presented here where vitamin B12 deficiency and psychiatric symptomatology were coexistent, and the patients recovered only on a combination of B12 supplementation and psychiatric medication.