Several reasons have been given why students should have contacts with real patients early in the undergraduate medical curriculum, i.e., in the preclinical phase. However, it is not clear exactly what effects early patient contacts have with regard to knowledge construction and the development of clinical reasoning skills. We sought students' views of the effects of preclinical real patient contacts on their learning, knowledge construction and development of clinical reasoning. Twenty-four students in the third and last preclinical year of a 6-year undergraduate medical programme were divided into three focus groups which met twice, after which saturation was reached. The discussions were recorded and transcribed. Summaries of the discussions were approved by the students after some modifications. Atlas-ti software was used to create a coding framework resulting in identification of main themes and sub themes. Early patient contacts motivate students to study, help them understand the impact of illness on patients' lives, and enhance professional socialisation and memory processes. Students distinguish between analytic and non-analytic clinical reasoning in connection with real patients. Analytic reasoning involves clinical and basic science knowledge. Non-analytic reasoning involves pattern recognition and is made possible by experiential learning from different patient contacts. The students indicate that seeing real patients early in their training has several positive effects on their learning. The contacts enhance knowledge construction and clinical reasoning. Although our results will have to be validated by quantitative, observational and experimental research, they imply that educational benefits are to be gained from real patient contacts in the preclinical phase of medical education.