Atenolol is a hydrophilic betareceptor blocking drug, which is predominantly eliminated via the kidneys, only about 5% of the atenolol is metabolised by the liver. After oral administration atenolol is incompletely absorbed from the intestine, so about 50% of the beta blocker are finally biovailable. In plasma only 3% of atenolol are protein-bound. There exists a linear relationship between the atenolol plasma levels and the degree of beta blocking effect measured by inhibition of the exercise-induced tachycardia. No correlation was found between plasma levels of atenolol and blood pressure lowering activity of the drug. After oral administration elimination half life of atenolol is calculated from 6 to 9 h by different authors. In patients with impaired renal function elimination half life of atenolol gradually increases to values of 36 h in uraemic patients (glomerular filtration rate (GFR) less than 10 ml/min). Between GFR and atenolol plasma clearance as well as renal clearance a close significant correlation is described. Prolongation of elimination half life requires a dosage adjustment of atenolol in patients with renal failure. A marked interaction of atenolol is found when calcium or aluminium hydroxide are concurrently administered with the beta blocker whereas cimetidine does not influence atenolol kinetics.