Scholars across different disciplines use Twitter to promote research and to communicate with society. Most conferences nowadays have their unique hashtag in which participants can communicate in real time. Previous research has reported on conference participants' use of Twitter, but no such studies are available in the field of mental health nursing. Thus, the explicit aim of the present study was to examine conference participants' use of Twitter during the 42nd International Mental Health Nursing Conference. Freely-accessible data were mined via a social media platform under the hashtag #acmhn2016. The total dataset consisted of 1973 tweets, and was analysed with descriptive statistics and a directed content analysis. The results demonstrated that 37% of the tweets were original posts, and 63% were engagements. In total, 184 individual accounts engaged in Twitter during the conference, and 16.4 tweets were posted hourly. Most tweets were categorized as conference/session-related content, but Twitter was also used for socializing with other participants. The most frequently-used words mirror a clear connection to a person-centred approach, and deviate from the biomedical terminology. However, not all of the conference participants engaged on Twitter, and might thereby risk being excluded from this backchannel.