TSC1/hamartin is a tumor suppressor gene involved in the development of various malignancies, including bladder cancer. In vitro studies showed that hamartin controls cell proliferation partly by up-regulating p27 and 14-3-3sigma. This study was designed to explore the value of these biomarkers in predicting outcome in pTa/pT1 tumors and validate the regulation of p27 and 14-3-3sigma by hamartin in vivo using human bladder cancer tissue. A tissue microarray of 134 pTa and pT1 tumors was constructed, and sections were stained with hamartin, 14-3-3sigma, and p27 antibodies. In multiple Cox regression analysis, pTa/pT1 tumors with reduced or low expression of hamartin tended to have higher risk of progression (P = .030). High-grade tumors tended to be at higher risk of progression in comparison with low-grade tumors (P < .001). The combination of expression of these 3 biomarkers did not add predictive value regarding disease outcomes. Low hamartin expression and high tumor grade are independent factors in predicting faster pTa/pT1 tumor progression. In a subset of pTa/pT1 tumors, hamartin has a role in bladder carcinogenesis by positively regulating 14-3-3sigma and p27.