In rabbit and rat retinae, wholemounted preparations and 40 microm thick vibratome sections were processed for nitric oxide synthase (NOS) immunoreactivity and consecutive semithin sections were immunostained with anti-NOS and anti-GABA antisera, respectively. Two types of NOS-labelled amacrine cells were identified: type 1 cells with larger somata were intensely stained, and type 2 cells with smaller somata were weakly stained. A few displaced amacrine cells also showed NOS-like immunoreactivity. All these NOS-like immunoreactive neurons also expressed GABA-like immunoreactivity. Thus, nitric-oxide-containing neurons might constitute a subpopulation of GABAergic neurons in rabbit and rat retinae.