This study assessed patient satisfaction and its associated factors among male drug-using inmates utilizing a prison detention clinic in Taiwan. A cross-sectional design and structured questionnaire were employed to recruit 580 drug-using inmates into the study. The Patient Satisfaction Questionnaire Short Form (PSQ-18), developed by the RAND Corporation, was used as the basis for the short scale of patient satisfaction, and the research data were analyzed using the SPSS for Windows 20.0 statistical software package. The results showed that the research subjects had low patient satisfaction in all the factors assessed compared with the scale’s general norms. Among the original seven satisfaction subscales in this study, the highest score was for the financial aspects, and the lowest was for the amount of time spent with doctors. This study also investigated satisfaction with medical lab exams and the pharmacy at the prison’s clinic, and the satisfaction scores were higher than the original seven subscales. In multiple logistic regression analyses, the final model indicated that the inmates undergoing observed rehabilitation (OR = 13.837, 95% CI = 2.736–69.983) were more likely satisfied with prison detention clinic c than those serving prison sentences. Those inmates with custodial deposits (high vs. low; OR = 1.813, 95% CI = 1.038–3.168), and meet their physical health needs (met vs. unmet; OR = 4.872, 95% CI = 2.054–11.560) had significant correlated with detention clinic care satisfactory level. Although there is only one study setting cannot give a generalizability for people who are incarcerated in Taiwan, this study highlights that the prison authorities should scrutinize factors associated with detention clinic care satisfaction, such as the type of inmate, economic status in the prison, self-reported health status, and their physical health needs, to increase the level of patient satisfaction.