The activity of glycine (250 and 500 mg kg(-1), twice daily, i.p.) was assessed in the olfactory bulbectomised (OB) rat, a model used to detect antidepressant activity. Removal of the olfactory bulbs in rats is associated with a variety of behavioural changes such as hyperactivity in the 'open field' apparatus. Previous studies have shown that chronic antidepressant treatment can reverse this behavioural effect. In the present study, there was an increase in ambulation scores in the 'open field' test in OB controls which was reversed by chronic treatment with glycine (500 mg kg(-1)). Intraperitoneal injection of 10 mg kg(-1) phencyclidine (PCP) produces an increase in locomotor activity in the home cage activity of sham operated whereas the PCP induced response was reduced in olfactory bulbectomised animals. Glycine reversed this OB deficit following chronic administration. It is concluded that parenteral administration of glycine displays antidepressant-like activity in the OB rat model of depression.