BackgroundThere are many professional associations representing chiropractors and chiropractic in the United Kingdom (UK). Each has its unique selling points (USPs) and chiropractors can choose to join as many as they like; however, cost of membership has to be weighed against perceived benefits. The predictors of UK chiropractic association membership and motivational factors to join these associations, have not formally been identified. This research study aimed to identify some of the factors and motivations in Welsh Institute of Chiropractic (WIOC) Alumni regarding their decision to join (or not) a UK chiropractic professional association.MethodsAn online survey instrument, comprising 23 questions, was administered from November-December 2015 via a link announced on ‘The WIOC Alumni’ Facebook group (N = 655), the active platform for the WIOC Alumni Organisation.ResultsOne hundred forty-eight respondents (approximately 22.6 % of ‘The WIOC Alumni’ Facebook group membership) completed the survey. Ten factors were reported to be important in decision making: ‘promoting public awareness of chiropractic’ (91.2 %), ‘access to professional indemnity insurance’ (89.2 %), ‘overall professionalism of the association’ (87.2 %), ‘the identity of the association’ (77.7 %), ‘positive attitude to research’ (77.0 %), ‘workplace support and advice’ (68.9 %), ‘access to events \\ courses \\ seminars’ (64.2 %), ‘Continuing Professional Development (CPD) activities’ (62.2 %), ‘cost of membership’ (59.5 %) and ‘addresses my area of interest’ (56.1 %). ‘Many of my friends have joined’ (71.6 %) was considered unimportant, whereas ‘Lobbying: Influencing policy’ and ‘career development’ were considered important by almost twice as many as those that consider them unimportant (45.3 %: 25.7 % and 43.9 %: 27.0 % respectively), ‘requirement of employment’ and ‘associations newsletter’ were seen as unimportant by roughly twice as many as those considering them important (44.6 %: 28.4 % and 35.8 %: 28.4 % respectively). Should it become an option, almost 71 % of respondents would support the unification of the four main UK chiropractic associations, (the British, McTimoney, Scottish and United, Chiropractic Associations: BCA MCA, SCA and UCA, respectively).ConclusionsSeveral factors have an important effect on motivations to join UK chiropractic professional associations. Further research is required to determine if this is WIOC specific or can be extrapolated more generally.Electronic supplementary materialThe online version of this article (doi:10.1186/s12998-016-0115-x) contains supplementary material, which is available to authorized users.