The purpose of this research is how WhatsApp as a medium of preaching by the Islamic religious extension office of the Ministry of Religion of Asahan district during the Covid-19 pandemic. This research method uses descriptive analysis with a qualitative approach. The results obtained through this research are the implementation of communication elements in the research as follows: (1) Communicators, Islamic religious extension agents of the Ministry of Religion, Asahan Regency; (2) The message in question is a message of da'wah. (3) Communists are Muslim communities in Asahan Regency who are members of the majelis taklim or recitation groups formed by extension agents; (4) Channels, using tools in the form of microphones, loudspeakers, and video recording applications as well as whatsapp; 5. Effect, is the expected result after a lecture by the Islamic religious extension agents in Asahan Regency. In carrying out his preaching through the WhatsApp application, there are obstacles so that the da'wah is not optimal, namely: (1) Technical obstacles, smartphone ownership is not evenly distributed among the congregation; (2) Physical or organic obstacles in the form of limited internet quota; (3) Geographical location of the congregation makes signal difficult; and (4) Thought barrier in the form of different opinions of the congregation in responding to the use of WhatsApp as a medium of preaching. The conclusions obtained are that whatsapp as a da'wah medium has met the elements of communication and the implementation of da'wah is hampered by (1) technical obstacles; (2) physical or organic barriers; (3) Geographical; and (4) retardation of thought.