I don't think so. Some cancer patients use marijuana to reduce the nausea produced by chemotherapy, but I have never heard it touted as a pain-killer.
See below. Note "anodyne" means "serving to assuage pain." From Herbs that Heal: Prescription for Herbal Healing by Michael A. Weiner, Ph.D and Janet A Weiner, 1994:
Marijuana: This illegal weed has proven to be an effective treatment for glaucoma and an aid for cancer patients undergoing chemotgherapy.
Currently an illegal drug in almost every country of the world, Cannabis has enjoyed a long and respectable history as a medicinal agent....Cannabis was formerly utilized in medicine to treat insomnia, allay pain, and sooth restlessness...Cannabis has been given in the treatment of neuralgias, spasmodic coughs as in pertussis and asthma, as well as in tetanus and hydrophobia and other painful spasmodic diseases...[I]t was recognized in the 1918 U.S. Dispensatory as a general nerve sedative for use in hysteria, mental depression, and neurasthenia.
...Although many refer to Marijuana as a "narcotic" or "hallucinogen," in a strict scientific sense neither term is applicable. Marijuana is not "addicting,"nor does it produce true hallucinations, except in extremely high does. Its anodyne and soporific action resembles that of Opium, but without the undesirable aftereffects of constipation and appetite loss.
Recent clinical experience demonstrates that Cannabis has a wide range of useful applications in medicine. Certain types of glaucoma that are resistant to conventional types of treatment can be controlled by smoking Marijuana. Administration of THC to cancer patients who experience nausea and vomiting as a common side-effect of chemotherapy produces relief of those symptions.[bold in original text]
Based on results of human studies, other remarkable effects of THC are to relieve pain, control seizures of epilepsy, relieve symptoms of asthma, and to act as a sedative. It is now well established that the use of Marijuana in the treatment of pain, to induce sleep, and for other maladies, has been fully justified on the basis of solid scientific evidence. Indeed if it were not for the undesirable mind-altering side effects, Marijuana would probably be widely used in the practice of medicine.