Phycoerythrins from the ceramiaceous red algae Campylaephora crassa (Okamura) Nakamura and related species, C. hypnaeoides J. Agardh and Ceramium kondoi Yendo, were investigated for absorption spectra, protein bands by gel electrophoresis and antigenic reactivity to anti-phycoerythrin using Ouchterlony double diffusion and immunoblot. Similarities in absorption spectra, showing peaks at ca. 566 nm > 534 nm > 495 nm, were found between C. crassa and Cm. kondoi, while C. hypnaeoides differed slightly. There were no differences in fluorescence emission spectra and protein bands between C. crassa and related species tested. Since Ouchterlony double diffusion, however, showed that phycoerythrins from C. crassa and Cm. kondoi were similar in antigenic reactions, and differed from that of C. hypnaeoides, the taxonomic position of C. crassa should be reinvestigated using other experimental approaches.