Diabetes mellitus is the most common metabolic disorder worldwide. To date, there have been no reports on the frequency of use of herb medicines in the managements of diabetes mellitus in Jordan. This cross-sectional study was conducted by interviewing 310 diabetic patients visiting two medical centers in Jordan: Jordan University of Science & Technology Medical Center and Sarih Medical Center between December 2003 and August 2004. It is found that 31% of interviewed patients have used herbal products (96 patients). The results revealed that the most commonly used herbs by diabetic patients in Jordan were Trigonella foenumgraecum (22.9%), Lupinus albus (14.6%), Allium sativum (11.5%), Allium cepa (5.2%), Nigella sativa (7.3%), Zea mays L. (6.3%), Urtica dioica L. (8.3%), Eucalyptus globules LA (9.4%), Olea europea L. (3.1%), Cumminum cyminum (9.4%), Coriandrum sativum (10.4%), Salvia officinalis L. (3.1%), and Tilia cordata (1%). Furthermore, it is found that 47.9% of the patients used herbs according to advice from their friends on a daily basis. The side effects were reported by 36.5% of the patients and include headache, nausea, dizziness, itching, palpitation, and sweating. Among the patients, 72.9% used the herbs as adjunctive therapy along with their anti-diabetic drugs and 80.2% of the patients informed their physicians about their use. A 79.2% of the sample confirmed their intention to re-use these herbs as 86.5% of them were satisfied with their diabetes control. There was a significant relationship between the use of herbs, the patient's place of residence and his/her level of education. The main conclusion of this survey is that the use of medicinal herbs among diabetic patient in Jordan is common. Therefore, it is essential to increase the level of awareness among diabetic patients and health care providers regarding the efficacy and toxicity of these medicinal herbs.