Since its approval in the United States, fentanyl has become increasingly popular for the medical management of pain and as a substance of abuse. Fentanyl is unique among the opioids in its widespread use with a transdermal delivery system, which contributes to its unique pharmacokinetics and abuse potential. We examined the demographics of deaths with fentanyl identified on toxicologic analysis and reviewed specific challenges in the laboratory detection of postmortem fentanyl levels. The New Mexico Office of the Medical Investigator database was searched for all cases from January 1986 through December 2007 with fentanyl reported as present or quantified. Those deaths with a cause of death identified as drug overdose were then analyzed separately. From 1986 to 2007, 154 cases were identified with fentanyl present in postmortem samples, with 96 of the cases identified as fentanyl-related drug overdoses. The number of fentanyl-related deaths has increased over the past 20 years, corresponding to both statewide increases in the medical use of fentanyl and the abuse of prescription opioids. The demographics of these fentanyl-related overdoses showed that subjects were more likely to be female, white non-Hispanic, and older than those in previously described overdose deaths. Several cases were identified with central and peripheral blood samples and antemortem and postmortem samples available for fentanyl quantification. Given the uncharacteristic demographics of fentanyl-related deaths and the complexity of the laboratory analysis of fentanyl, forensic scientists must use caution in both the detection and interpretation of fentanyl concentrations.