Two chromatographic methods are developed and validated to estimate Atazanavir Sulfate and Ritonavir in new fixed dosage form, that is, tablet dosage form named Synthivan. The first method is based on HPLC separation of the two drugs on the reversed phase HiQSil C18 column (5 µm, 250 × 4.6 mm) at ambient temperature using an isocratic solvent system consisting of acetonitrile and water in the ratio 52:48 (v/v). Quantification is achieved with a PDA detector at 254 nm at a flow rate of 1.5 mL/min. Linearity of concentrations is found at 60–600 µg/mL and 20–200 µg/mL for Atazanavir sulfate and ritonavir, respectively. The second method is based on HPTLC separation of the two drugs on pre-coated silica gel 60F₂₅₄ aluminum plates using toluene:methanol:glacial acetic acid:ethyl acetate (7:0.5:1.5:2, v/v/v/v) as solvent system followed by densitometric measurements of their spots at 254 nm. The linearity of the concentration is found to be 30–300 and 10–100 ng/spot for Atazanavir Sulfate and Ritonavir, respectively. Both methods are validated according to ICH guidelines. The analysis of variance (ANOVA) and Student's t-test are applied to correlate the results of Atazanavir Sulfate and Ritonavir determination in dosage form by means of HPLC and HPTLC method.