Objectives: One of the major complaints of addicts in withdrawal period is their malady and boredom. This study aims to examine the effectiveness of problem solving skills on happiness of addicts to methamphetamine in Tehran city. Method: Using a semi-experimental design and multistage cluster sampling method, 36 addicts were randomly selected and assigned to the experimental and control groups. Both groups filled Oxford Happiness Questionnaire in the pre-test, posttest and after three-month follow up. The participants of the experimental group were taught problem solving skills. Covariance and variance analysis with repeated measurement of Bonn-Ferny test were conducted to analyze the data. Result: Considering the presence of ETA square (0.28), it can be concluded that the experimental intervention led to changes in the treatment group that resulted in 0.28 total changes due to the intervention. We can say that with 99% confidence, there is a statistically significant difference between the mean of the study groups in the three intervention stages. Conclusion: Training problem solving skills is effective in increasing happiness level of addicts to methamphetamine. Keywords: problem solving skills, happiness, methamphetamine, addicts
