Saffron is the dried stigmata of the flowers of saffron (Crocus sativus L., Iridaceae). Saffron has various pharmacological effects and is regarded as a potent drug. Thus research on the biological activities of saffron and its active constituents may have clinical and public health applications. To evaluate the basic and clinical pharmacology of saffron and its active constituents, the English papers in the data bases EMBASE, SCOPUS, MEDLINE, SCIENCE DIRECT, CHEMICAL ABSTRACTS, English and Persian papers in the data base SID and proceedings of the Iranian physiology and pharmacology congresses and Iranian congresses concerning saffron were retrieved by using keywords comprising Crocus sativus, anti-tumor, anti-oxidant, anti-genotoxic, memory, neuroprotective, analgesic, anticonvulsant, opioid dependence, antidepressant, cardiovascular, lipids, respiratory, gastric ulcer, immune system, ocular, antimicrobial and toxicity and their Persian equivalents from 1975 until November 2008. The investigations demonstrate that saffron and its active constituents have anti-tumor, anti-oxidant, anti-genotoxic, memory and learning enhancing, neuroprotective, analgesic and anti-inflammatory, anticonvulsant, opioid abstinence syndrome alleviating, antidepressant, hypotensive, hypolipidemic, insulin resistance reducing, tissues oxygenation enhancing, bronchodilator, antitussive, gastric ulcer preventive, Immune-stimulator, retina protective and antibacterial effects. In view of the existing deficiencies in the conducted researches, further clinical trials, pharmacokinetic and toxicological studies concerning saffron are recommended.