Background: Ceriops decandra (Griff.) Ding Hou is used conventionally for managing a number of therapeutic conditions including diabetes, haemorrhage, pain, diarrhea, angina, and dysentery etc. Furthermore, Ceriops tagal Linn is used to treat hemorrhage, acariasis, wound infection, malaria, malignant diabetes and ulcers etc in folk medicine. The present study was designed to evaluate the comparative pharmacological activities of leaves of these two medicinal plants of the Sundarbans. Methods: Antioxidant activity was assessed by total phenolic, total flavonoids, total tannin content, and DPPH free radical scavenging assays. Acetic acid-induced test for analgesic, oral glucose tolerance test for antihyperglycemic, open field test for neurobehavioral, prothrombin time test for anticoagulant, anthelmintic potential on Paramphistomum cervi, and in-vivo cytotoxicity test on brine shrimp nauplii were used for appraising pharmacological activities of both extracts. Results: C. decandra extract revealed greater radical scavenging activity than that of C. tagal. C. decandra extract significantly (P < 0.05) reduced writhing inhibition of 54.55% and 66.37% at 500mg/kg and 250 mg/kg, respectively. In oral glucose tolerance test, C. decandra significantly lowered the blood glucose level for pretreated mice with glucose by 25.76%, 2272%, and 31.88%, 38.71% respectively, at 60 min and 120min at the 250 mg/kg, and 500 mg/kg dose level. But, the reduction of blood glucose level by C. tagal extract was less than that of C. decandra. Furthermore, C. decandra produced a sedative effect at both doses starting from 30 min to 120 min of experimental period. The crude extract of C. decandra and C. tagal delayed the prothrombin time in a dose dependently. The C. decandra and C. tagal produced dose-dependent paralysis and death time. The LC50 values obtained from brine shrimp lethality bioassay were 94.69, 114.29 µg/mL for C. decandra and C. tagal, respectively. Conclusion: C. decandra revealed prominent pharmacological activities than that of C. tagal. Also, the present study confirmed the scientific evidence of both plants.