This research aimed to investigate the effect of relationship marketing on brand advocacy within mobile telecommunication companies. The research followed a deductive approach and utilized quantitative analysis as the main research methodology.Data was collected through a questionnaire, resulting in 402 valid responses. Structural equation modeling was then used to test the proposed hypotheses. The findings confirmed that relationship marketing has a positive effect on brand advocacy. Moreover, the research showed no significant demographic differences in respondents' opinions, except for differences related to education level and age. The data was analyzed using SPSS V. 26 and AMOS V.23.Data was collected through a questionnaire, resulting in 402 valid responses. Structural equation modeling was then used to test the proposed hypotheses. The findings confirmed that relationship marketing has a positive effect on brand advocacy. Moreover, the research showed no significant demographic differences in respondents' opinions, except for differences related to education level and age. The data was analyzed using SPSS V. 26 and AMOS V.23.