This article reviews issues and opportunities related to greenhouse and screenhouse cover materials and presents industry perspectives. A literature survey shows that various greenhouse cover materials (glass, rigid and flexible plastic sheets and screens) are used in different regions of the world. These materials differ in their physical, chemical, mechanical and radiometric properties. Selection of the type of cover material by growers depends on many factors and is mainly affected by local tradition, which is related to the geographical climate, solar radiation intensity, crop value, cost of the cover material and its life span. Over the years, cover materials have been improved to enable higher light transmittance, a change in the characteristics of the transmitted light, reduced heat loss and hence higher energy saving and prevention of condensation and droplet formation on the inner surface of the cover. Furthermore, properties of cover materials have been changed to enable reductions in insect invasion into greenhouses/screenhouses on the one hand and to improve orientation of beneficial insects in the house on the other. Nowadays, different glass surface treatments or suitable cover materials, and sometimes a combination of the two, are in the vicinity to be used in order to increase the uniformity of the greenhouse climate and enhance plant growth, for example, diffused glass that scatters the light. Next to that, micro structures are combined with nanostructures, such as anti-reflection treatments (AR-glass), and also hydrophilic film with anti-fog additives, which can be used in order to improve light transmission. Recently, solar cells were incorporated into cover materials to generate electricity and semi-transparent plastic sheets that can generate electricity were developed and tested. In addition to the topics mentioned above, this article considers the deterioration of cover materials as a result of different environmental effects. It also briefly presents methods to measure properties of cover materials.