Distribution, growth rate, and carbonate production of non-geniculate and unattached coralline red algal beds (rhodoliths) were studied in the Gulfs of Panama and Chiriquı´ along the Pacific coast of Panama. This is the first attempt to quantify coralline carbonate production in this region based on a newly developed algorithm. Although situated at the same latitude, the two gulfs are characterized by distinctly different environmental conditions; Chiriquı´ is mesotrophic throughout the year, whereas the Gulf of Panama is eutrophic due to intense seasonal upwelling. Coralline algal carbonate production is 103 greater in the Gulf of Chiriquı´ (11.258 3 1010 gr CaCO3 yr21) than in the Gulf of Panama (1.69 3 1010 gr CaCO3 yr21), which is characterized mostly by siliciclastics with minor carbonates. Corallines display a patchy distribution in both gulfs being concentrated mainly around the islands. In Chiriquı´, they occur as thin crusts as well as massive-nodular and openbranching growth types; encrusting types are most common in the Gulf of Panama. Growth rates of branching corallines were calculated based on annual growth bands matched to their skeletal Mg/Ca ratios. Ratios are higher in the less dense portions of growth bands corresponding to higher growth rates during the dry season, whereas both Mg/Ca ratios and growth rates in the dense portions (wet season) drop. Growth rates of branch tips in both sites are similar to those reported from other temperate-subtropical regions. Extremely slow growth rates combined with the old ages of individual thalli document the overall stability of this algal ecosystem.