The paper deals with a systematic study of the Chiton collections from the Andaman and Nicobar Islands present in the Zoological Survey of India. Opportunity was also taken to examine the Type specimens available in the National Zoological Collections.

Of the 7 genera and 12 species represented in the collection one species namely, Callistochiton pulchellus (Gray) originally reported from the Peruvian Coast (East Pacific) has now been recorded for the first time from the Indian Ocean. Also another species viz., Acanthochiton mahensis Winckworth hitherto known occurring along the coast of the mainland India is now recorded from the Nicobars. The distribution of each species is as given completely as possible and the Zoogeographical significance is also discussed.

This study reveals that out of 12 species as many as 6 species are found to be common both to Indian Ocean and West Pacific regions, while 4 others are known from the Indian Ocean only. A solitary species is found to have a wide distribution in Atlantic, Pacific and Indian Oceans. Another species which was hitherto occurring only in East Pacific appears to have found its way into the Indian Ocean also.