At least 20 species in Ranunculaceae, the buttercup family, are reported as having been used medicinally by 19 different groups of native peoples in British Columbia and adjacent areas. These species are known to contain the skin-irritating, blister-causing compound, protoanemonin, in their fresh state. Protoanemonin is almost certainly the active principle involved in many of these medicinal applications. A majority involved the use of the plants as external poultices for boils, cuts, abrasions and other skin sores. Other disorders having a high frequency of treatment with ranunculaceous species include: muscular aches, colds and other respiratory ailments, and general, unspecified illness. Native groups in other parts of North America also used many ranunculaceous species as poultices, and for colds, headaches and many other ailments. A number were used for stimulation and "revival" of unconscious persons. It is suggested that the protoanemonin contained in these plants may have, through several different mechanisms, positively influenced the healing process physiologically and not just psychologically. If future research confirms this, these protoanemonin containing plants may have potential in certain treatments in modern medicine.