Dietary supplements are believed to enhance athletic performance and/or prevent/reverse pathological states. Despite the increasing use of dietary supplements in Saudi Arabia, systematic studies in this field are lacking. This study aims to assess the relation between demographic and social characteristics and dietary supplement use among adult males in Saudi Arabia. Demographic and dietary supplements data from fitness club participants were collected through a questionnaire, and the Pearson chi-square test was used to determine associations. A total of 448 apparently healthy adult males above 20 years of age, who were registered at fitness centers located in Saudi Arabia, participated in the study. The majority (275 [62%]) of the study participants were younger (20–30 years), of normal weight (189 [43%]), without health problems (332 [79%]), and obtained an undergraduate degree or higher (336 [77%]). The majority (58%) took supplements under the supervision of a professional and the rest depended on Internet (22%), friends (12%), or books (4%) for choosing supplement types. The main motives of the participants for visiting the fitness center were: weight loss (N = 149 [35%]), keeping fit (N = 101 [24%]), and muscle building (N = 151 [35%]). One hundred and fifty-five participants (44%) were taking supplements on a daily basis with 34 (10%) having taken it for a prolonged duration (>1 year). The most commonly used supplements were proteins (29%) and multivitamins (21%). Supplement use was not associated with the participants’ family income or level of education but was positively associated with younger age (<31 years), χ2(2, N = 443) = 4.96, p = .03.