We investigated the effects of propofol and propofol–ketamine on hemodynamics, sedation level, and recovery period in pediatric patients undergoing cardiac catheterization. We performed a prospective, randomized, double-blind study. The study included 60 American Society of Anesthesiologists physical status II or III (age range, 1 month–13 years) undergoing cardiac catheterization for evaluation of congenital heart disease. Propofol and ketamine were prepared in 5% glucose solution to a final concentration of 5 and 1 mg/ml, respectively; similar injectors containing 5% glucose solution only were prepared. Fentanyl (1 μg/kg) and propofol (1.5 mg/kg) were given to both groups. Then, group 1 received 0.5 ml/kg of 5% glucose and group 2 0.5 ml/kg of ketamine solution by an anesthesiologist who was unaware of the groups of patients. Local anesthesia with 1% lidocaine was administered before intervention in all patients. The noninvasively measured mean arterial pressure, heart rate, respiratory rate, and peripheral oxygen saturation were recorded at the baseline, following drug administration, at 3, 5, 10, 15, 20, and 30 minutes and then at 15-minute intervals until the end of the procedure. Additional drug and fentanyl requirements to maintain a sedation level of 4 or 5 were recorded. After the procedure, the time to a Steward recovery score of 6 and adverse effects in the first 24 hours were recorded. The number of patients with more than a 20% decrease in mean arterial pressure was 11 in group 1 and 3 in group 2 (p < 0.05). The number of patients who experienced more than a 20% decrease in heart rate was 12 in group 1 and 5 in group 2 (p = 0.054). Ten patients in group 1 and 3 patients in group 2 required additional fentanyl doses (p = 0.057). The number of additional propofol doses was lower in group 2 (p < 0.05). Propofol combined with low-dose ketamine preserves mean arterial pressure better without affecting the recovery and thus is a good option in pediatric patients undergoing cardiac catheterization.