ABSTRACTHydroxychloroquine is used in the treatment of malaria due to its pharmacological activity and with minimal adverse effects. Hydroxychloroquine is used in treatment of the diseases like rheumatoid arthritis and lupus erythematosus. In some countries, it is also indicated in the prevention or treatment of malaria. It has been developed in the 1950s from chloroquine, an old anti-malarial drug. COVID-19 is a highly contagious disease, transmitted through respiratory droplets by affected person through sneezing, coughing, talking, which also spread by touching a contaminated surface or may object. The person infected with the disease shows flu-like symptoms such as fever, muscle pain, cough and sore throat in five to six days after infection, while some patients may remain asymptomatic carriers. The disease further develops severe pneumonia in the patients. The mortality rate is high in patients with underlying conditions and those aged 60 years and above. This review complies about the mechanism, precautions, toxicity, ongoing trials of hydroxychloroquine and their medicinal usage. Keywords: Chloroquine, Clinical trials, COVID-19, Hydroxychloroquine.