Simvastin, a HMG-CoA reductase blocker, is used for the treatment of certain forms of hypercholesterolaemia. Simvastin is prescribed to lower high serum levels of cholesterol by inhibiting a specific enzyme, hydroxy-methylglutarylCo-enzym-A (HMG-CoA) reductase. This ultimately leads to an increase of the number of LDL-receptors in the liver, and thus, to a decrease of the serum LDL-cholesterol. To a much lesser extent it lowers the serum VLDL-cholesterol and makes the serum HDL-cholesterol level rise. In general, this relatively new compound is well tolerated and only a few, mostly minor, adverse effects have been reported so far. We present a patient who developed interstitial lung disease with pleural effusion most probably as a result of the use of Simvastin.