The objective of this study was to investigate of plasma concentration and pharmacokinetic parameters after off-label use of selamectin. One years of ago, 12 ewes and 12 female goats were used in this study. In both groups, a single dose of 12 mg/kg selamectin (Stronghold® 12% 240 mg) was administered topically. During the 35 days following administration, blood samples were taken with different intervals and required analyzes were conducted. Plasma concentrations of selamectin were analysed by high performance liquid chromatography (HPLC). As a result of analyzes, for sheep mean plasma concentration, maximum plasma concentration (C_max), the area under the concentration-time curve (AUC), the mean residence time (MRT) and time to reach peak concentration (T_max) values determined as 1427.27±90.52 pg/mL, 4.78±0.61 ng/mL, 810.35±115.95 ng.h/mL, 10.86±0.89 days and 72 hours, respectively and for goats these values were determined as 1195.03±70.81 pg/mL, 3.27±0.52 ng/mL, 664.42±72.62 ng.h/mL, 10.46±0.74 days and 72 hours, respectively. As a result, plasma concentration, C_max and AUC values were found higher in sheep compared to goats (P<0.05) and there was no significant difference between MRT and T_max values (P>0.05) using selamectin topically in sheep and goats.