The use of herbal medicines among Nigerian patients and the tendency to combine this class of medicines with allopathic drugs while on hospital admission have been on the increase. Earlier studies show that community pharmacists from Nigeria believe that they need more training to counsel patients on their use of herbal medications. Objective: To evaluate knowledge base, use, acceptability, attitudes and beliefs of hospital pharmacists and physicians in South-western Nigeria on herbal products / phytopharmaceuticals /dietary supplements (HP/PP/DS). Methods: A 20-odd questionnaire including an 8-item herbal medicine question was used to assess the knowledge of the physicians and pharmacists in the area of pharmacology of HP/PP/DS. Effects of demographic information such as age, sex, year post graduation, years of experience and area of specialization on the scores obtained were evaluated using Fisher’s exact tests. Level of significance was set at p<0.05.Results: Pharmacists (51.4%) believed that the training they had was not adequate while physicians (44.6%) believed HP/PP/DS are not safe and 18.5% believed they are not effective. Pharmacovigilance centres were not significantly used for adverse reactions reported by patients. Pharmacists (67.6%) and physicians (29.3%) believed phytopharmaceuticals interact with other drugs. Year of graduation had a significant effect on the perception of the possibilities of interaction for pharmacists. 5.6% of the physicians and 62.4% of the pharmacists scored ≥50% with the questions on use and interaction potentials of HP/PP/DS, with cadre and years of practice having significant effects. Conclusions: There is a deficiency in the knowledge base of physicians, especially on the pharmacology and potential interaction of herbal medicines. There is an urgent need for the inclusion of pharmacology of common herbal medicines in the curriculum of Nigerian medical degree and an improvement in the pharmacy curriculum in this area.