The objective of this study was to evaluate the performance of a low-cost method, the Thin Layer Agar (TLA), for the diagnosis of smear-negative patients. This prospective study was performed in Homa Bay district Hospital in Kenya. Out of 1584 smear-negative sputum samples, 212 were positive by Löwenstein-Jensen (LJ) (13.5%) and 220 positive by TLA (14%). The sensitivity of LJ and TLA was 71% and 74 % respectively. TLA could become an affordable method for the diagnosis of smear-negative tuberculosis in resource-limited settings with results available within 2 weeks.