Heavy metal toxicity related to the use of traditional medicines has been reported worldwide. Heavy metals may be introduced into medicinal plant products through various anthropogenic process such as mining, contaminated agricultural resources etc.

Poisoning from heavy metal contamination of medicinal plant products has caused countless health challenges including liver and kidney failure and even death. Hence, monitoring the content of mineral elements in medicinal plants and their extracts is of particular importance. This study investigated the heavy metal contents of six medicinal plants obtained from Onigambari Forest Reserve Oyo State. Using an atomic absorption spectrophotometer, the heavy metals Lead (Pb), Zinc (Zn), Cadmium (Cd), Copper (Cu), Mercury (Hg), Chromium (Cr) and Magnesium (Mg) were assessed. Lead, Cd, Hg and Cr were absent in the medicinal plants analyzed in this study.

The concentrations of Zn ranged from 0.20ppm in Khaya grandifoliola to 0.40ppm in Khaya ivorensis and 0.30 Magnifera indica. Copper concentration ranged from 0.015 ppm in Khaya grandifoliola to 0.23 ppm in Garcinia kola; while that of Mg was 0.55 ppm in Kigelia africana. The heavy metal content of most of the Medicinal plants were below WHO/FAO permissible limits.