This research was conducted to find the indigenous diatom species unrecorded in Korea from February to December 2016. The samples were taken at 28 sites of the coastal regions on the west coast of Korea and Jeju Island. Diatoms were collected mostly from sand and mud of tidal flats, including gravel, seaweed on the bottom and macrophytes floating in the seawater. Diatom specimens were observed by means of light and scanning electron microscopy. Twenty one species were discovered and added as new specimens to the Korean diatom flora, which are divided into 9 orders, 12 families, and 16 genera. The list and photographs of the species are included with the description of the morphological characteristics and distribution in Korea.

INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSION
 ACKNOWLEDGEMENT
 REFERENCES

• Byoung Seok Kim(Department of Oceanography, College of Ocean Science & Technology, Kunsan National University)
• So Yeon Kim(Department of Oceanography, College of Ocean Science & Technology, Kunsan National University)
• Jong-Gyu Park(Faculty of Marine Applied Biosciences, College of Ocean Secience & Technology, Kunsan National University) Corresponding author
• Andrzej Witkowski(Palaeoceanology Unit, Faculty of Geosciences, University of Szczecin, Poland)