This study explored the moral reasoning and scientific argumentation skills of 31 gifted Finnish adolescents participating in a science program at the University of Helsinki. Students were given the Defining Issues Test (DIT) to determine their level of moral reasoning and the Raven test to evaluate their scientific reasoning. The argumentation skills of students who scored exceptionally high on the DIT were then compared with those of students who received average scores in moral reasoning. In qualitative essays and interviews, students were asked to identify moral dilemmas in science and provide solutions for them. Analysis focused on the principles students used in justifying the right moral judgment in science. Findings indicated that the argumentation skills of the pupils who scored high on the DIT differed from those pupils who received average scores. Furthermore, the principles used in solving moral dilemmas in science by high-scoring pupils differed from the ones used by those gifted pupils who received average DIT scores. Two individual case studies contrast the argumentation skills of students with either a high or low score on the DIT. (Contains 18 references.) (DB)