Two simple, accurate, and precise HPTLC methods have been established for the determination of mexiletine hydrochloride, an antiarrhythmic agent, in Mexicord capsules. Analyses were performed in horizontal chambers on RP C18F254s and normal-phase amino (NH2) HPTLC precoated plates with the mobile phases tetrahydrofuran-citrate buffer, pH 4.45 (3 + 7, v/v) and chloroform-tetrahydrofuran-hexane-ethylamine (3 + 2 + 5 + 0.1, v/v/v/v), respectively. The plates were developed for a distance of 40 mm in both cases. Densitometric measurements were achieved in the UV mode at 217 nm based on peak areas with semilinear calibration curves (R2 > or = 0.97) in the concentration range 0.5-8.0 microg/spot for the NH2 and C18 HPTLC methods. The elaborated chromatographic methods were validated in accordance with International Conference on Harmonization guidelines in terms of linearity, accuracy (99.64% for NH2 and 99.53% for C18), precision (intraday RSD 1.16 and 2.71%, respectively), sensitivity (LOD 0.1 microg/spot for both systems), and specificity.