Acupuncture combined with drugs has been widely used in the treatment of various clinical conditions and can produce a stronger or more beneficial curative effect than either separate acupuncture or chemical drug does. However, the mechanisms underlying the additive or synergetic effects of acupuncture plus drugs are not well understood so far. Based on careful review and analysis of the literature accumulated, the authors proposed several aspects possibly involving the additive or synergetic effects produced by acupuncture plus drugs. For instance, acupuncture stimulation at acupoints may influence the drug concentration in blood and/or in target organ and the bioavailability of the drug via modulating the drug absorption, distribution and metabolism in the body. In addition, the curative effect of drug may also be strengthened by acupuncture stimulation via altering the signaling pathways of the targeted specific receptors and via potentiating the resultant responsiveness or sensitivity of the cells in the target organ in responding to the drugs administered. The ideas mentioned above may raise the novel clues for further studying the mechanisms underlying acupuncture-produced increase of the curative effects of medicines.