This study is based on 25 well documented reports of cases which responded well to treatment with Petroleum. Materia medica data were compared with results in contemporary clinical practice. Many patients had characteristic skin problems; children often had recurrent or chronic upper respiratory tract problems. The most prominent mental feature is a quiet, withdrawn or stubborn disposition. The mental symptoms may be difficult to recognise. Detailed documentation in daily practice can be helpful for preserving data of the effect of a medicine; confirmation of statements given in materia medica; improving understanding of homeopathic medicines and differentiating the indications for medicines.