The systematic relationship of the unicellular red algae based on their morphological, physiological and habitual characteristics was discussed by referring to the results of their molecular phylogenetic analyses, using 18S rRNA and psbA genes. Five groups (named as one ancestral stock; Porphyridium Group (-G) and other four groups; Rhodospora-Rhodella-, Rhodosorus-and Cyanidium-G) previously reported were partially supported by the molecular phylogeny which showed four phylogenetic groups. However, two of them made a clade with multicellular ones. In the basic framework of the systematic relationship of uncellular reds has to be reconstructed, after taking new findings of molecular information into consideration. The correspondence with the phenetics and phylogentic relationships of unicellular reds is the center of the present Mini-review.