This study reports shell morphometric relationships (height/length and width/length) for the most common and abundant bivalve species of the Algarve coast (southern Portugal). The individuals were caught during periodic exploratory fishing surveys carried out during 2000 using artisanal fishing gears (clam dredge and razor clam dredge), on soft bottoms in the subtidal zone down to 25 m depth. For this particular study, a total of 7497 bivalves were sampled, belonging to 25 species distributed in 9 Families. Almost all regressions were significant (P