1 An experiment with hyoscine butylbromide has been used to demonstrate how drug effects differ in intensity and time course after intravenous (20 mg) and subcutaneous (40 mg) injection with and without massage of the injection site. It also demonstrates how objective and subjective observations may be related, and gives students practice in the interpretation of experimental data. 2 The experiment takes about 2 h, and the effects of the drug have worn off completely after about 3 hours. 3 The structure of the discussion of the experiment and its results with the students are described to draw attention to the questions that can be asked of the data. The results obtained with 41 subjects are summarized to illustrate this discussion. 4 Various ways of modifying the experiment to suit other teaching objectives are mentioned. The need to consult the local Ethics Committee before undertaking experiments on students is emphasized.