Plancktonic foraminifera in middle Miocene marine sediments in the Penedes basin (NE Spain) have been examined. Using the findings of chronostratigrapbic markers in representative basin sections, identification of Langhian materials and hypothetical biostratigraphical correlations among sections have been established. Besides, the existence of Burdigalian deposits in the lower samples of the sections studied, reflecting the lower-middle Miocene transition, has been been established. The foraminifera species used are: Praeorbulina glomerosa sicana (DE STEFANI), Praeorbulina transitoria (BLOW), Globigerinoides bisphericus TODD and Globigerinoides altiaperturus (BOLLI)