The interest in medicinal plants is not only due to the fact that it is a source of food additives, but it is also a major source of medicines. Medical plants contain many important vital ingredients used in the treatment of many diseases. Therefore, medicinal plants are considered a safe source of medical drugs. Many medicinal plants have a significant economic importance to increase their demand. The plant families include many families, such as solanaceae family, which is one of the largest plant families with more than 3000 plant species And the plants of this family contains many important biological components and because of its importance, it was necessary to study and identify these plants by making fingerprinting, detect the molecular genetic markers for this family, study the genetic diversity of these species and determine the relationships between  species of this family by using genetic techniques such as the technique of  Inter simple sequence repeat (ISSR). The results obtained in the five solanaceae species (Lycium shwaii, Hyoscyamus muticus, Solanum nigrum from Northwestern coast, Solanum nigrun from Saint Katherine, and Nicotiana gluca) indicated that, 6 primers were applied. The HB15 primer which gave 12 bands, showed the highest polymorphism 58.33%, and the 49A primer, which gave 6 bands gave a lowest polymrphism 16.66% between the used plants populations, these results mean that ISSR technique is an powerful tool to make genetic diversity assessment for species.