Glucose tolerance, total plasma cholesterol and plasma triglycerides were studied in the genetically hypertensive obese Koletsky rats (SHR/N-cp) and in their lean siblings. The initial part of the glucose tolerance curve was substantially elevated in both obese and lean Koletsky animals compared to normotensive Wistar rats. The abnormal glucose tolerance in hypertensive rats was accompanied by increased total plasma cholesterol and plasma triglycerides. Long-term treatment with dopaminergic agonists terguride or bromocriptine (0.2 and 2.0 mg/kg/day, respectively) exerted similar effects on lipid metabolism but both drugs differed in their influence on glucose tolerance. Terguride lowered plasma lipids and normalized glucose tolerance in both obese and lean Koletsky rats. Bromocriptine reduced hyperlipidaemia but did not attenuate the abnormalities of glucose tolerance in either lean or obese Koletsky animals.