The histological scrutiny of the brain ofPoecilobdella viridis revealed two types (A and B) of neurosecretory cells, which are classifiedon the basis of size, shape and tinctorial characters. A cells are spheroid, rarely pyriform, with size (cell area) varying between 608 μ to 1701 μ. Their cytoplasmic granules take violet colouration with AF and deep red with Mallory’s triple stains. B cells are elongate or oblong with a size (cell area) ranging between 516 μto 831 μ. Their cytoplasmic granules are coloured blue to violet with AF and pink with Mallory’s triple stains. Neurosecretory material staining intensity of these cells is described light microscopically.