Actinobacteria refers to a group of Gram-positive bacteria with higher G + C DNA base content than other groups of bacteria. They belong to one of the largest bacterial genera called Actinomycetes and are known for their enormous ability to adapt to any environment (including the less explored biota such as deep sea or oceans, hydrothermal vents, etc.). It is a well-established fact that the group actinobacteria is pharmacologically very important and is highly efficient in producing secondary metabolites (such as pigments, antibiotics, toxins, alkaloids, etc.). These species have been further screened for many important and novel secondary metabolites that show a range of biological activities including anti-angiogenesis, antibacterial, anticancer, antifungal, anti-inflammatory, antimalaria, anti-parasitic, antioxidant, antitumour, antiviral, etc., to name a few. The secondary metabolites extracted from actinobacteria of the marine milieu have received extensive consideration due to their structural diversity and exceptional biological activities. Some of the actinomycetes genera such as Actinomadura, Actinoplanes, Microbispora, Micromonospora, Nocardia, Pseudonocardia and Sinomonas are known as rare species, which needs to be exploited for its applications in the field of pharmaceuticals (drug discovery). In the current chapter, an assessment is being done on the research conducted with the marine actinobacteria and the secondary metabolites produced by them of pharmaceutical importance. These secondary bioactive substances possess discrete chemical assemblies which may help in the catalysis or synthesis of new drugs. It is believed that the actinobacteria can provide promising and favourable productivity of commercially important bioactive compound with therapeutic value. © Springer Nature Singapore Pte Ltd. 2020.