Background. In Republic of Congo, malaria diagnosis still widely relies on microscopy. We aimed to evaluate the performance of routine microscopy for malaria diagnosis at three different health centers in Brazzaville. Methods. A total of 259,416, and 131 patients with clinical signs of uncomplicated malaria were enrolled at the Hopital de Mfilou, Centre de Sante Integre "Maman Mbouale," and Laboratoire National de Sante Publique, respectively Two thick blood smears were prepared for each patient, the first being examined by routine microscopists and the second by expert. Results. At the Hopital de Mfilou, sensitivity was 62.1% and specificity was 67.3%. Positive and negative predictive values were 55.6% and 72.9%, respectively. At the Centre de Sante Integre "Maman Mbouale," sensitivity was 94.2% and specificity was 33.6%. Positive and negative predictive values were 50% and 89.1%, respectively. At the Laboratoire National de Sante Publique, sensitivity and specificity were high with 91.7% and 94.9%, respectively. Positive and negative predictive values were 64.7% and 99.1%, respectively. Conclusion. The performance of routine malaria microscopy in Brazzaville remains inaccurate with large variations among different health centers. Therefore, repeated training including supervision and evaluation would improve routine malaria diagnosis for better management of malaria in Brazzaville, the Republic of Congo.