A wide range of conditions cause generalized splenomegaly. Anesthetic induced splenic enlargement in fractious dogs may interfere with radiographic interpretation of their pathologic splenomegaly. The aim of this study was to compare sedative effects of acepromazine (0.3 mg/kg, IM) and propofol (8 mg/kg, IV) on splenic size in dogs using radiography. Ten young (1-4 years old), clinically normal mongrel dogs (20-25 kg) were used in this study. Left lateral and ventrodorsal radiographs were prepared prior to, and 10, 30, 60, 120 minutes as well as 24 hours after administration of each drugs. The greatest length and width of the spleen was measured using caliper in millimeter. Significant splenic enlargement was seen 10, 30 and 60 min after intramuscular administration of acepromazine (P< 0.05), but no significant enlargement was seen after intravenous injection of propofol. In conclusion, acepromazine is not a suitable sedative drug as chemical restraint for evaluation of splenic size in abdominal radiography of dogs. In contrast, propofol is a rapid and short acting anesthetic drug that can be administrated without any complication in fractious dogs before radiological examinations of spleen.