Nicotine metabolite ratio (NMR) has been positively associated with increased cigarette consumption, greater lung cancer risk, and decreased smoking cessation. Opioid-dependent populations experience higher rates of smoking, difficulties with smoking cessation, and more negative smoking-related health outcomes compared to the general population of smokers. Opioid agonist treatment medications (OAT; i.e., methadone or buprenorphine) might influence NMR and thereby explain some of these disparities. The current study investigated the associations of OAT status (i.e., receiving OAT vs. no OAT), OAT type (i.e., methadone vs. buprenorphine), and OAT dose (i.e., low vs. high dose) on NMR in samples drawn from two prior studies examining the effects of very low nicotine content cigarettes among vulnerable smoker populations. Although OAT status per se was not significantly associated with NMR, methadone was significantly associated with higher NMR relative to those receiving buprenorphine or no OAT in one study sample. Exploratory analyses did not reveal a significant effect of methadone low vs. high dose on NMR, but an effect of buprenorphine dose was observed such that those receiving higher doses of buprenorphine had higher NMR relative to low doses. This suggests that methadone might be associated with increased nicotine metabolism, though the relationship between OAT and NMR is complex.