Evaluation of accuracy of three common dilution methods for drugs.Perspective double blind investigation from March to June 1995.Anaesthesia and Resuscitation Service of Children's Hospital of Iglesias (CA).Forty dopamine at 2/1000 samples, obtained by dilution of dopamine at 40/1000 on sale with three different methods by five different operators, were analysed with a chromatography system in liquid phase at high pressure.Mean concentration with difference not exceeding 5% from the goal, are considered acceptable. Only one group of samples was found to be into these limits, but it was also the most dangerous for the high percentage of great mistakes in dilution. Although there are significant differences in the accuracy and safety of the three dilution methods, the highest and lowest final concentrations obtained differ very much from those estimated.It is suggested that drugs confections with proper dilution for different clinical uses might be on sale.