The art of glassmaking has been a significant and valuable tradition in Iran throughout history. After the establishment of Islam in Iran, in the 3rd and 4th centuries AH, the art of glassmaking has undergone a period of development and prosperity, and many glassworks have been made and left by glassmakers during the given centuries. The author intends to study the morphology of Iranian glass cups by examining the components of each work, including fixed and variable elements. Thirty samples of Iranian glass cups have been studied to answer this basic question “What are the visual characteristics of glass cups of the 3rd-4th century AH of Iran in terms of fixed and variable form elements?” This research is based on library studies and descriptive-analytical methods. The results of this study show that glass cups are made of a fixed part of the body which can be divided into three general categories: simple cylindrical, horny, and narrow waist. Base, decorations, and motifs are among the variable elements of these works that have caused differences between these works. The base is also applied in three modes wide, narrow, and long by the glass artist on the bottom of the cup. The decorations and motifs of glass cups can be traced in two categories purely abstract and iconic-abstract, including geometric, non-geometric, written, plant, and animal motifs. Most of Iran’s glass cups are adorned with pure geometric abstract decorations. Geometric patterns often include circles, concentric circles, triangles, and rhombus, and horizontal lines are often visible in the upper margin of the body of Iranian glass cups. Non-geometric patterns are also used by the glassmaker not as abstract but as fillings of the empty space of the body, although these motifs have been used in two works alone. Two glass cups feature pure abstract ornaments in Kufic script, conveying themes of blessing for the vessel’s owner. Icon-abstract animal decorations on Iranian glass cups include bird, eagle, cow, and four-limbed animal motifs. Nine cases of glass cups were ornamented with animal motifs. In addition to being used alongside other motifs, plant-based iconic decorations are embossed on eight specimens of glass cups alone. It is worth mentioning that most of these works have a combination of motifs and geometric and non-geometric motifs, geometric and written motifs, plant and animal, etc. which have been used together toward the taste of the glass artist.