Aim: One of the cheapest, easiest and most effective ways to detect testicular cancer early is to resort to early detection screening methods associated with health beliefs about testicular cancer, and the second is to self-examine the testicles. In the country, there are a limited number of studies on the health beliefs and early diagnosis behaviors of young adult men for testicular cancer. For this reason, the study was conducted to determine the effect of online education given to young adults on testicular cancer health beliefs and behavior.

Material and method: The research was conducted as a randomized controlled experimental study. The study population consisted of 768 individuals who applied to Family Health Centers affiliated to Agri Provincial Health Directorate between April 2021 and June 2022, and the sample of the research consisted of 90 individuals selected from the population using the improbable random sampling method. "Descriptive Feature Form", "Champion's Health Belief Model Scale in Testicular Cancer Screenings" were used to collect data. In the analysis of data; percentile distribution, chi-square, Fisher-Freeman-Halton Exact test, t-test in independent groups, Repeated Measures ANOVA Test, Friedman Test, One Way ANOVA test, Kruskall Wallis test, and post hoc analyzes (Bonferroni, Games Howell, Dunn) were used.

Inclusion Criteria:

• Being 18-35 years old,
• Being literate,
• Computer can be used,
• Being able to access the Internet,
• Not having a testicular diagnosis before,
• Deciding to participate in the research.

Exclusion Criteria:

• Being outside the age range of 18-35,
• To be diagnosed with testicular cancer before