The study is set to evaluate the role of online media in promoting advertising” (A Study of Some Selected Advertising Agencies). The rationale for carrying out this study was informed by the interest to know the extent to which advertising agencies use new media in this advanced technology. The survey research method was used while the questionnaire was adopted as a data collection instrument. 150 copies of questionnaires were administered and 142 respondents that were purposively selected in some advertising agencies in Ikeja Lagos. The data collected were analyzed using frequency and percentage table. Findings show that advertising agencies still use traditional mass media more than new media, they said the media selection is determined by the media cost, audience reach, and audience interest. It is recommended that students of advert and marketing be thought especially on the Integrated Marketing Communication (IMC) especially to ensure understanding of the new media among others while online payment for products and services such as money perfect, credit card, debit card, online signed cheque, PayPal and other should be protected while many easier ones should be designed to make online payment easier, effective and fraudulent free.