Background: Noninvasive treatments are frequently used in treatment of superficial basal cell carcinoma (sBCC) because of better cosmetic results, lower costs, and less burden on health care services when compared with surgical excision. However, probability of treatment failure is higher after noninvasive therapies and may depend on histologic tumor characteristics. Objective: We sought to investigate whether tumor thickness and adnexal extension are determinants of treatment failure in sBCC treated with topical methylaminolevulinate-photodynamic therapy, imiquimod, or 5-fluorouracil. Methods: Data were derived from a randomized controlled trial on the effectiveness of methylaminolevulinate photodynamic therapy, imiquimod, and 5-fluorouracil for treatment of sBCC (ISRCTN79701845). For tumors with treatment failure (n = 112) and a randomly selected control group of tumors without treatment failure (n = 224) data on tumor thickness and adnexal extension were retrospectively collected. Treatment failure was defined as a clinically and histologically persistent or recurrent tumor within 1-year posttreatment. Results: Tumor thickness of included patients ranged from 0.2 to 1.0 mm. Tumor thickness and adnexal extension of sBCC were not significantly associated with treatment failure of methylaminolevulinate photodynamic therapy, imiquimod, or 5-fluorouracil. Limitations: Follow-up period of 1 year is a limitation. Conclusion: There seems to be no need to determine tumor thickness or adnexal extension in sBCC before treatment.