"NCIS" can be seen on the CBS network, on Tuesday night. After each episode has aired, it can be viewed online via a pay-for-service subscription called "CBS All Access" at CBS.com.
Earlier seasons of "NCIS," however, have been syndicated and are now available on the USA Network. The show has proven to be so popular, that the USA Network often airs back-to-back episodes, which the network calls NCIS Marathons. The popularity of the show has extended worldwide, and it is presently dubbed or subtitled into 20 different languages.
As of 2015, "NCIS" is not available to view via the Netflix online streaming service.