Coffee, consumed for its refreshing and stimulating effect, belongs to the tribe Coffea of the subfamily Cinchonoidea of Rubiaceae family. Coffee is a complex chemical mixture composed of several chemicals. It is responsible for a number of bioactivities and a number of compounds accounting for these effects. Few of the significant bioactivities documented are antioxidant activity, anticarcinogenic activity, antimutagenic activity etc. Various compounds responsible for the chemoprotective effects of coffee are mainly polyphenols including chlorogenic acids and their degradation products. Others include caffeine, kahweol, cafestol, and other phenolics. Coffee also shows protective or adverse effects on various systems like the skeletal (bone) system, the reproductive system, the nervous system, the cardiovascular system, the homocysteine levels, the cholesterol levels etc. Harmful effects of coffee are associated with people who are sensitive to stimulants. Overall, with the available information, it can be concluded that the moderate consumption, corresponding to 3 to 4 cups/day with average strength is safer to human health.