Intravenous anesthetic delivery in reptiles can be challenging. Current injectable techniques have varied induction/recovery times and anesthetic quality. This study hypothesized that intracoelomic administration of a new anesthetic, fospropofol, in turtles would result in dose-dependent anesthesia and respiratory depression. A two-part prospective trial using adult red-eared slider turtles (Trachemys scripta elegans) weighing 764 ± 17 g was conducted to determine an effective anesthetic dose and to evaluate the anesthetic quality, duration, and respiratory effects of an efficacious dose. In part 1, six turtles were randomly administered 25-mg/kg (low-dose [LD]) and 50-mg/kg (high-dose [HD]) fospropofol in a crossover design. Respiratory rate, immobility, and muscle relaxation scores were evaluated for 180 min. In part 2, eight turtles were administered HD fospropofol. Immobility and muscle relaxation (front and hind limb) scores and time to endotracheal intubation/extubation were evaluated until scores returned to baseline. In part 1, the LD group had significantly lower immobility and muscle relaxation scores versus the HD group over time (both P < 0.05); scores were significantly elevated from baseline for 20–120 min and 15–180 min, respectively (all P < 0.05). Although not significantly different between groups (P > 0.05), respiratory rate was significantly decreased from baseline from 10 to 120 min (all P < 0.05). In part 2, HD fospropofol decreased respiratory rate from 21.5 ± 2.9 breaths/min to 0.1 ± 0.1 breaths/min, similar to the results in part 1. Maximal reductions in mobility and front and hind limb motor tone occurred at 39.0 ± 4.1, 30.8 ± 3.6, and 24.0 ± 3.6 min, respectively. Intubation in 7/8 turtles occurred at 45.7 ± 5.4 min and extubation at 147.0 ± 23.2 min. However, 2/8 turtles showed prolonged anesthetic effects, requiring resuscitative efforts for recovery. Due to the unpredictable quality and duration of anesthesia with intracoelomic fospropofol, it should be used with caution for general anesthesia in red-eared sliders at the doses and administration route investigated.