The biometric relationships for two populations of the bivalve mussel Brachidontes pharaonis collected monthly during the period from January 2014 to December 2014 from the intertidal zones of Adabia and Ain Sokhna coasts at the north-western portion of Suez Gulf were studied. The obtained results showed that there is a good relation between length and total body weight represented by allometric regression coefficients (b) being 2.112 and 2.376 for Adabia and Ain Sokhna populations, respectively. The overall value for relative condition factor “kn" varied from 0.83 to 1.22 and from 0.67 to 1.41 and averaged 1.01±0.13 and 1.02±0.22 for the two populations at Adabia and Ain Sokhna, respectively. These values denote to good well-being or fitness, but were not stable between different size classes; being higher in smaller individuals at size class 2.5 mm but decreased in the following size classes between 5 and 12.5 mm, and increased slightly again in the medium sized and larger individuals. The present results also showed that, the relations between both length and breadth as well as between length against width were allometric with regression coefficients “b “values less than “1" and were represented by 0.66 and 0.74 for the two variables respectively, at Adabia, but increased slightly to 0.74 and 0.85 at Ain Sokhna. These data show that, available habitats and favorable conditions being better at Ain Sokhna than Adabia. The length frequency distribution for the whole populations at the two sites  were represented by 5 size classes, denotes to population stability controlled by continuous nearly equal adding for juveniles and removal by different mortality rates.