Tuberculosis is one of the major causes of death worldwide, millions of people have been infected with pulmonary tuberculosis and over 95% of tuberculosis deaths occur in low and middle income countries as per World Health Organization report. The study assessed the performance of Ziehl Neelsen technique and GeneXpert used for diagnosis of Pulmonary tuberculosis in Uasin Gishu county health facilities, Kenya, between November 2019 and February 2020. A cross-sectional study was conducted in three selected health facilities and a total of 104 participants were enrolled into the study. Sputum samples from suspected tuberculosis patients were tested using Ziehl Neelsen technique, GeneXpert and culture method was used as gold standard. Performance of the tests was done by considering their sensitivity, specificity, predictive values. The results indicated that among the 104 sputum samples tested Ziehl Neelseen technique used detected 23(22.1%) bacilli from spot samples and 33(31.7%) bacilli from morning sputum samples. GeneXpert test detected 49 (47.1%) bacilli. The results also revealed that there was significant difference between Ziehl Neelsen technique using spot samples and GeneXpert and culture test (p-value< 0.05) and Ziehl Neelsen technique using morning test done with culture test had no significant difference (p-value>0.05). Performance of tests should be done accurately for proper diagnosis of TB, GeneXpert should always be used since its sensitivity is high and also detects Rifampicin resistance. Also, Performance of tests should be done using standard procedures to avoid errors in the test results.