Introduction It is essential to strengthen the treatment of latent tuberculosis infection (LTBI) to break the chain of transmission. The drug used worldwide for the treatment of LTBI is Isoniazid. A clinical trial conducted in Brazil has demonstrated the bioequivalence of Isoniazid in the 300 mg formulation with 3 tablets in the 100 mg formulation. Further studies are needed to evaluate the completion of treatment with Isoniazid 300 mg single tablet. Objective Describing a protocol for a clinical trial to evaluate the completion of treatment of LTBI with the drug Isoniazid in 300 mg tablet formulation compared to the use of Isoniazid in 100 mg tablet formulation. Methods This is a pragmatic, multicenter, randomized, open-label clinical trial registered on the Rebec RBR-2wsdt6 platform. Individuals 18 years of age or older with an indication for treatment of LTBI will be included, with only 1 individual per family nucleus. Individuals whose index case of active TB is categorized as retreatment, multidrug-resistant and extremely resistant, individuals transferred from the original center two or more weeks after the onset of treatment, and persons deprived of liberty will be excluded. The study intervention will be the treatment of LTBI with 1 tablet of Isoniazid 300 mg. The control group will receive the treatment of LTBI with 3 tablets of Isoniazid 100 mg. Follow-up will be performed at month 1, month 2 and at the end of treatment. The primary outcome will be completion of treatment. Conclusion It is expected that with the treatment with the 300 mg formulation, more patients will complete the treatment based on the complexity index of pharmacotherapy. Our study intends to substantiate theoretical and operational strategies that respond to the demand for incorporation of a new formulation of the drug for the treatment of LTBI in the Unified Health System network.