This study sought to identify factors associated with intention to change sexual practices among heterosexual Thai males diagnosed with sexually transmitted infections (STIs). STI clinic patients (n = 247) reported their sexual behaviors and condom use during the previous 3 months. STI and HIV knowledge, motivation to change sexual practices, and behavioral skills were assessed. Then, self-reported behavior change intention, including consistent condom use, reducing number of sexual partners, not using drugs and alcohol when having sex, and refusal of condomless sex, was examined. Consistent condom use in the past 3 months by Thai males diagnosed with STIs was low across all types of sexual partners (lover 17.2%, casual partner 24%, and sex worker 71.4%). Risk reduction self-efficacy (p < 0.001), perceived benefits from condom use (p < 0.001), perceived barriers to condom use (p < 0.001), perceived risk for HIV (p < 0.05), and STI and HIV knowledge (p < 0.05) were significantly correlated with behavior change intention. Significant predictors of behavior change intention were risk reduction self-efficacy (p < 0.001), perceived benefits of condom use (p = 0.016), and perceived risk for HIV (p = 0.033). They explained 36% of behavior change intention variance. Intervention aimed at enhancing motivation and behavioral skills to adopt preventive behaviors should be developed to prevent recurrent STIs, including HIV infection, among heterosexual Thai males diagnosed with STIs.