To evaluate the reliability of self assessment as a substitute for follow up, 30 self reported assessments of length, width, and colour of abdominal scars were compared with those of clinicians. The degree of disagreement between patients and medical observers was not significant. We conclude that as long as instructions to patients are unambiguous, reliable information may be obtained by postal inquiry. Self reported measurements may thus replace time-consuming follow up visits in studies on the influence of various factors on scar tissue.