"My greetings to all Swayamsevaks as the RSS completes 90 years in service of the Nation," Modi, who had also worked as an RSS pracharak, tweeted.
The RSS was founded in September 1925 by Keshav Baliram Hedgewar on Dussehra day.
In his annual Dussehra address in Nagpur, RSS chief Mohan Bhagwat praised the Modi government for lifting the country from the mood of "despondency" and "creating an atmosphere of "hope and confidence" in the country, while enhancing its standing on the global stage.
Union minister Nitin Gadkari and Maharashtra Chief Minister Devendra Fadnavis among several others attended the event.
