Various cancers and tumorous conditions were treated by healers. A total of 47 plant species belonging to 42 genera and 30 families were documented and identified as anti-cancer and anti-diabetic herbal remedies in Northern Peru, with 31 plants used for diabetes treatment and 17 species used for conditions identified by local healers as cancer. Most species used were Asteraceae, followed by Gentianaceae. Asteraceae as the most important anti-cancer and anti-diabetic family was clearly overrepresented in comparison to the overall medicinal flora. The majority of anti-cancer and anti-diabetic herbal preparations were prepared from the leaves of the employed plants. Leaves and stems were more often used than characteristic for the overall medicinal preparations found in the region, while whole plants were employed less frequently. This indicates that the local healers count on a very well developed knowledge about the properties of different plant parts. In almost 60% of the cases fresh plant material was used to prepare remedies, which differs little from the average herbal preparation mode in Northern Peru. Over 90% of the remedies were applied orally. This is significantly different from the regional average of application. Over half of all remedies were prepared as mixtures with multiple ingredients by boiling plant material either in water or in sugarcane spirit. Little scientific evidence exists to date to prove the efficacy of the species employed as anti-cancer and anti-diabetic remedies in Northern Peru. Only 38.71% of the plants found to be used for diabetes treatments and 17.65% employed as anti-cancer remedies or related species in the same genus have been studied at all. Traditional medicines are still the main and often only choice for a large part of the global population. The information gained on frequently used traditional remedies against cancer and diabetes related illnesses might give some leads for future targets for further analysis in order to develop new drugs. However, more detailed scientific studies are desperately needed to evaluate the efficacy and safety of the remedies employed traditionally.