Caffeine definitely increases the force of the heart beat. Yet Wood, “Notice of Judgment Under the Food and Drugs Act No. 1455 1912,” says such an effect may be desirable since a slower rate and increased force induce cardiac efficiency. Heavy coffee drinking may produce a frequent, hard pulse and palpitations, but this again goes over into the territory of abuse. Coffee tends both to dilate the vascular system and to constrict it, the net result being a mass movement of the blood without increased blood pressure. Coffee has repeatedly been suspected of damage to the heart and blood vessels but such suspicions are common in therapy and evidence is entirely lacking to prove this point scientifically. Suspicion is here probably no more legitimate than in many lay superstitions. While patients with definite heart trouble should avoid all stimulants the normal use of coffee by an adult cannot be said to have an insidious effect upon the heart and blood vessels. While coffee is a diuretic it cannot be convicted of renal injury as yet. Indeed it is quite probable that the kidneys become accustomed to caffeine while A. R. Cushny (J. Pharmacol. & Experimental Therapy 4 363) declares that caffeine does not injure the kidneys even when given in large dosage over long periods. But how about digestion? Years ago Fraser (J. of Anatomy & Physiology 184 13 1883) said that coffee and tea hindered the digestion of protein foodstuffs with the exception of ham and eggs! This very fortunate immunity renders the typical American dish a safe breakfast in any case. In general, however, observations _in vivo_ indicate that the amounts of the beverage usually taken have no evil effects upon digestion. Indeed some investigators have found a pronounced increase in gastric secretion following tea and coffee. Hutchinson in his “Food and Dietetics” says that the digestive disturbance caused by such infused beverages is negligible in health. Others have held that the aromatic constituents of coffee, or the “empyreumatic oil,” upset digestion. There may be some reason for this; at least certain individuals tolerate much better coffee from which these substances have been removed. Caffeine is of course a stimulant to the central nervous system, particularly that part of it intimately associated with the gastric function. How far is its use as such a cerebral stimulant advisable? Like all stimulants this will result in greater fatigue on excessive usage. But as “The Medical Review of Reviews” once said, “When tea and coffee are made moderate in strength and partaken of in sober quantities they are gentle stimulants and their effect upon the nervous system is salutary.” A too constant reliance on coffee as a goad may of course result in nervous irritability.