Illicit drug/s use (IDU) among university students is a public health concern. We assessed the associations between socio-demographic, academic, and health and lifestyle characteristics (independent variables) and regular, occasional or never IDU (dependent variables). Data were collected across seven faculties (1177 students) at the University of Turku (Finland) via an online questionnaire. About 1.5% of the sample had regular IDU, 19% occasional IDU, and 79% never IDU. Independent predictors of ever (lifetime) IDU included males [adjusted odds ratio (AOR) 1.82, P = 0.001], not living with parents (AOR 2.59, P < 0.001), singles (AOR 0.51, P < 0.001), lower religiosity (AOR 1.49, P = 0.022), better self-rated general health (AOR 0.41, P = 0.003), higher health awareness (AOR 1.93, P = 0.014), more depressive symptoms (AOR 1.82, P = 0.004), daily smokers (AOR 3.69, P < 0.001), heavy episodic drinking (AOR 2.38, P < 0.001) and possible alcohol dependency (AOR 2.55, P < 0.001). We observed no independent associations between ever IDU with age, study discipline, perceived stress or academic performance. The 20.5% ever IDU is concerning. The compelling independent predictors of ever IDU included not living with parents, lower religiosity, daily smokers, heavy episodic drinking and possible alcohol dependency (AOR range 2.38â3.69). Education and prevention need to emphasize the negative consequences to reinforce abstinence from IDU. Health promotion could focus on beliefs and expectations about IDU and target students at risk for successful efforts.