The incremental cost-effectiveness ratio indicated that it would cost an additional $AUD79 to achieve an extra stimulant-free day with modafinil compared with placebo. This result was not statistically significant, but appeared to be a robust estimate after sensitivity analysis. Counselling, whether received within program or from other services, improved the cost-effectiveness of modafinil relative to placebo. Strategies to improve the uptake of counselling are recommended as cost-effective. Cost and outcome data were collected alongside two randomised controlled trials of modafinil 200 mg daily over 10 weeks for methamphetamine (n = 74) and cocaine dependence (n = 8), respectively. Incremental cost-effectiveness ratios representing the additional costs to achieve a given outcome were calculated for both the change in the number of stimulant-free days and quality-adjusted life years 12 weeks post-treatment. (Published Abstract)