Introduction. Interpersonal psychotherapy (IPT) and antidepressant medication (ADM) are effective treatments for adult depression but there is inconclusive evidence regarding their comparative efficacy in reducing suicidal ideation. Moreover, little is known about which intervention works best in different age-groups. Individual Participant Data (IPD) meta-analyses give access to data on SI that often have not been reported in existing randomized controlled trials . Moreover, it allows for examining moderators of treatment effect at the patient level with more precise effect estimates than conventional meta-analyses. The aim of this IPD meta-analysis is to examine the comparative efficacy of IPT and ADM on suicidal ideation in depressed adults, and explore possible differences in this comparative efficacy between young adults (18-24 Years) and other adults (? 25 years). Methods. A comprehensive literature search was conducted in the databases PubMed, PsychINFO, Embase and the Cochrane Library until May 2023 to identify randomized clinical trials of IPT versus ADM in the acute phase treatment of adult depression. IPD were requested and analyzed using logistic mixed models The primary outcome was post-treatment suicidal ideation as assessed with the suicide-item of the Hamilton Depression Rating Scale. The secondary outcome was suicidal ideation at follow-up. Results. The literature search resulted in 15 RCTs meeting the inclusion criteria. IPD were obtained from 9 of these studies (N=1,536/1,948, 78.9%). 70.2% of the participants was female, with a mean age of 42.6 years (SD=13.4). Item-level HAM-D data were available for 6 studies totaling 990 participants (N=990/1948, 51.0%). These studies mainly recruited from clinical populations. IPT was applied in an individual format in all studies. The findings of these analyses on the comparative efficacy of IPT and ADM on suicidal ideation in general and in young versus other adults will be presented. Conclusion. To the best of our knowledge this is the first meta-analysis assessing the efficacy of IPT versus ADM on suicidal ideation. Working with IPD allows for the examination of age as a moderator on the individual patient level with increased statistical power. Clinical implications of the results will be discussed.