A specific method of analysis for actinodaphine HCl in plasma by UV secondary spectroscopy was established. The actinodaphine in plasma was extracted with chloroform, then the combined extracts were evaporated to dryness under room temperature. The residue was dissolved in 5 ml of 95% ethanol and the secondary derivative spectra was measured at wavelength of 400 nm to 240 nm Select their 316 nm and 330 nm as analytical wavelength. The D values of the derivative amplitude were measured with peak-peak method between 316 nm and 330 nm. The standard curve was linear over 0.5-20 micrograms/ml. The average recovery was 97.6 +/- 5.5%, the coefficient of variation was 5.64%. After intravenous administration of 10 mg/kg, the plasma concentration vs time data were fitted to curves employing a non-linear method based on a simple method in optimization theory. The statistical comparison (r2, F-test and AIC) of fits of one and two compartment model to plasma concentration time data indicated that the data would be described best by an open two compartment model. The pharmacokinetic parameters (mean +/- SD) were T1/2 (alpha), 0.705 +/- 0.142 min; T1/2 (beta), 17.869 +/- 5.383 min; K21, 0.292 +/- 0.035 min-1; K10, 0.145 +/- 0.054 min-1; K12, 0.621 +/- 0.153 min-1; Vc, 0.152 +/- 0.029 L/kg; Vp, 0.367 +/- 0.045 L/kg; Vd, 0.518 +/- 0.062 L/kg; Clr, 0.021 +/- 0.004 ml/kg; AUC, 492.263 +/- 101.574 micrograms.min.ml-1. These results show that actinodaphine HCl is distributed and eliminated rather rapidly without marked accumulation and the distribution is mainly in the blood.