The genetic and morphologic variation of Solea lascaris (Risso, 1810) was studied along the Portuguese coast through protein electrophoresis and morphometric and meristic analysis. Genetic analysis was based on 10 loci, all except one polymorphic. The average heterosigosity (H_T) was 0.116, a high value but within the range found for several flatfishes, and the analysis of F-statistics showed that this variation is mostly due to differences within populations. Genetic distances between samples were low and seem to agree to an isolation by distance model. Morphologic analysis was based on 11 morphometric characters and 7 meristic counts. Results show a high overlap between samples. Both genetic and morphological analyses indicated a great variability but suggested low levels of differentiation along the Portuguese coast. Nonetheless, genetic analysis showed that these levels were significant and population structure should be analysed using markers able to detect a greater degree of population differentiation.