Dengue is a mosquito-borne viral illness that infects humans. For the past few decades, it has been declared a global public health problem. The current study, conducted at the district headquarter hospital (DHQ) Bannu between June to September 2018, was based on the seroprevalence of antibodies against dengue virus serotypes and their hematological parameters among the patients. A total of 1738 individuals suspected of having dengue were diagnosed through NS1, IgG, and IgM antibodies and RT-PCR techniques. Of all the samples, 716 (41.19%) were found to be positive for dengue. A higher infection rate was found in males (65.92%) compared with females (34.07%). The most affected age group was 16-40 years, whereas the most affected tehsil was Bannu, where the DENV-3 serotype was prevalent. The rare serotype (DENV-4) was found in 1% of cases. Symptoms including fever (100%), myalgia (100%), headache (61.31%), vomiting (34.63%), and rashes were common among the dengue patients. However, the mild cases showed fewer clinical signs compared with the severely infected cases. The study also revealed a significant association (P < 0.05) between hematological parameters and dengue infection, showing a significant decrease in TC, eosinophils, neutrophils, and platelets and a significant increase in monocytes and lymphocytes. Based on the current report, it is concluded that patients with the above symptoms and hematological changes may have an increased probability of dengue and should be kept under observation to separate dengue-positive patients and to enhance the treatment process.