Three species of Triconia belonging to the conifera-subgroup are described from Korean waters (NW Pacific). A new species, Triconia hirsuta, was found that can be distinguished from its sibling T. conifera by a paired patch of long setules on the anterolateral margin of the genital double-somite in the female, and an unusual position of caudal seta II branching off at almost a right angle to the caudal ramus. Males have not been found so far. Both sexes of T. conifera (Giesbrecht, 1891) and T. borealis (Sars, 1918) from Korean waters are redescribed with the addition of morphological details and/or differences not noted in earlier descriptions. Morphological characters of Korean T. conifera are in close agreement with specimens described from the Mediterranean Sea and the Pacific, but differ in several parameters from T. conifera from the Red Sea, which is regarded as a distinct, though closely related, species requiring re-examination. Published data on the community structure and zoogeographical distribution of oncaeids of the conifera-type in the NW Pacific are summarized, and the remaining uncertainties concerning the distribution of species of the conifera-subgroup in these areas are pointed out.