Kuwait, which is located in the northwestern Arabian Gulf, has experienced several incidences of marine life mortality during the past two decades. Mortalities included pelagic and benthic fish, Sea Cucumbers and Mollusks including pearl oysters. Most of the mortalities occurred in Kuwait Bay, which is shallow and semi-enclosed. The Bay encompasses Sulaibikhat Bay, whose coastal waters are nutrient-rich and eutrophicated due to sewage discharge into its waters. Other mortalities were reported outside Kuwait Bay, especially in marinas and southern waters of Kuwait. Kuwait's marine environment has been increasingly affected by harmful algal blooms, which increased by frequency and severity. Other Gulf countries experienced serious mortality incidences as well. Different causes were responsible for the different marine mortalities in Kuwait and the region, including untreated sewage input, eutrophication, bacterial infection, algal blooms, hypoxic conditions, pollution, and dredging. The above mortalities impacted the economy, and affected aquaculture activities, the fishing operations, coastal tourism, damaged coral reefs, and forced the closure of desalination plants. This study summarizes the different mortality incidents that occurred in the northwestern Arabian Gulf during the period of 1999 to 2019 and their possible causes. Efforts, taken by Kuwait to improve the environmental conditions of the degraded coastal area of Kuwait Bay, include for example, the designation of a marine protected area in southern Kuwait Bay that would ensure the continued production of ecological services of the protected Bay area.