The evaluation of osteoarthritis pain is principally based on a subjective rating scale. Accuracy in recording pain score is obviously important. In the present study we evaluated the effect of better standardization of information given to patients in determining the visual analog scale (VAS) score. Fifty-three consecutive male and female outpatients aged 18-65 years (40 women and 13 men) fulfilling the criteria for osteoarthritis of the hands were included in the study. Eligible patients attended the Rheumatology Center on three occasions: day 1, day 3 and day 6 of the study. Two information cards were prepared. On the first card, given to the patient at the end of the first visit, osteoarthritis of the hands was described as a less dangerous disease than rheumatoid arthritis. On the second card, given to patients at the end of the second visit, greater emphasis was placed on anatomo-pathological description of the destructive lesions. VAS score was recorded on days 1, 3 and 6 of observation. ANOVA for repeated measures demonstrated a significant reduction of VAS score between the first and the second assessment and a significant increase between the second and the third assessment. A further significant difference was found in the comparison between the first and third assessment. These results show that different standards of information given to patients may modify VAS score.