The opioid-addicted subjects increases tend to risk behavior compared to healthy subjects, it is therefore important to indicate whether the administration of methadone reduces this trend.

Objective of the study was to assess the propensity for risk behavior in opioid-dependent individuals treated with methadone substitution therapy.

The study involved 85 opioid-dependent patients. To assess the tendency to the risk behavior Iowa Gambling Task (IGT) test was used. IGT test was conducted twice: before and about 1 hour after administration of methadone. 132 healthy individuals matched for age and gender were included to the control group and was tested twice at an about 1 hour interval.

At a similar level was the incidence of risk decisions and safe decisions in the group of addicts before the administration of methadone (49.9 and 50.1) and in the control group (49 and 51). After administration of methadone in a group of addicts and control group incidences of risk and safe decisions were changed. Statistically significant reduction (Wilcoxon matched-pairs signed-ranks, p < 0.05) of risk decisions (13.47%) and increase of safe decisions (13.42%) found after methadone administration in addicts persons.

After administration of single dose of methadone there was statistically significantly decreased tendency to risk behavior, which has reduced the incidence of risk decisions compared to the safe decision. The results indicate that in the opioid-dependent individuals treated with methadone substitution therapy a single dose of methadone has an impact on risk behavior as measured by IGT test.