The assessment of the radioactivity level and associated risks has been performed for the mangrove plants. Twenty-five mangrove samples were collected from the Abu Fasi, Marsa Shaab, and Sowmaa mangroves in the Marsa Shaab area of the Egyptian Red Sea coast. The activity concentration values of the nuclides 226Ra, 232Th, and 40K for samples collected from sediments associated with the mangrove environments were measured. The specific activities in mangrove samples obtained in the Abu Fasi region varied as follows: 15± 0.8 Bq.kg-1 to 42± 2.1 Bq.kg-1 for 226Ra, 10± 0.5 Bq.kg-1 to 39± 1.9 Bq.kg-1 for 232Th, and 103± 5.2 Bq.kg-1 to 340± 17 Bq.kg-1 for 40K. Additionally, the activity concentrations of the mangrove samples collected from Marsa Shaab and Sowmaa mangrove areas ranged as follows: 28± 1.4 to 56± 2.8 Bq.kg-1 for 226Ra, 18± 0.9 to 58± 2.9 Bq.kg-1 for 232Th, and 164± 8.2 to 531± 26.5 Bq.kg-1 for 40K. Moreover, the mangrove samples collected from the Sharm el El Madfea area showed activity concentrations ranging as follows: 25± 1.3 to 52± 2.6 Bq.kg-1, 15± 0.8 to 61± 3 Bq.kg-1, and 250± 9.1 to 583± 29.2 Bq.kg-1 for 226Ra, 232Th, and 40K, respectively. The highest average values were observed in samples collected from Marsa Shaab and Sowmaa mangroves for the 226Ra and 232Th. However, the highest average value for 40K was measured in samples collected from the Sharm El Madfea area. The radiation hazard calculations for the collected mangrove samples showed much lower values than the criterion and worldwide recommended limits.