Genodermatoses are not usually easily diagnosed by inexperienced physicians. We developed a computer program to aid their clinical diagnoses and compared its accuracy rate to those of five residents in dermatology. The database of the program contained the clinical findings of 100 genodermatoses. Findings related to the skin, its appendages, mucous membranes and physiognomy were recorded in detail; but the involvements of other organs, only as headings. Twenty test cases were prepared from previously published reports. Their clinical findings were evaluated both by the program and five residents, who were at the end of the third year of their training in dermatology. The program gave the correct diagnosis in all of the test cases, but the residents failed to do so in one to seven cases. The high accuracy rate of the program suggests that it can aid inexperienced physicians in their clinical diagnosis of genodermatoses.