An in-vitro method for diagnosing, stratifying, prognosing and/or monitoring a lung disease and/or a respiratory disease, comprising: (i) determining the value A nl of at least one rheological parameter on a sample of mucus A of a subject, in a non-linear region of the stress-strain curve of the sample; (ii) determining the value A l of at least one rheological parameter on said sample of mucus A, in a linear region of the stress-strain curve of the sample; and (iii) diagnosing, stratifying, prognosing and/or monitoring lung disease and/or respiratory disease from a comparison of said values A nl, A l determined with a respective limit value; wherein the rheological parameter determined in the non-linear region is selected from - the elastic modulus (G'), - the viscose modulus (G"), - the damping factor (tan δ), - the complex modulus (G*), - the critical deformation (γ c), - the flow stress threshold (τ c), - the elastic force, - the critical stress (σ c), and - any combination thereof; the rheological parameter determined in the nonlinear region comprising at least σ c; and wherein the rheological parameter determined in the linear region is selected from: - the elastic modulus (G'), - the viscose modulus (G"), - the damping factor (tan δ), - the complex modulus (G*), - the plastic deformation (γ p), - the plastic stress (τ p), and - any combination thereof; the rheological parameter determined in the linear region comprising at least G*. (i) determining the value A nl of at least one rheological parameter on a sample of mucus A of a subject, in a non-linear region of the stress-strain curve of the sample; (ii) determining the value A l of at least one rheological parameter on said sample of mucus A, in a linear region of the stress-strain curve of the sample; and (iii) diagnosing, stratifying, prognosing and/or monitoring lung disease and/or respiratory disease from a comparison of said values A nl, A l determined with a respective limit value; wherein the rheological parameter determined in the non-linear region is selected from - the elastic modulus (G'), - the viscose modulus (G"), - the damping factor (tan δ), - the complex modulus (G*), - the critical deformation (γ c), - the flow stress threshold (τ c), - the elastic force, - the critical stress (σ c), and - any combination thereof; - the elastic modulus (G'), - the viscose modulus (G"), - the damping factor (tan δ), - the complex modulus (G*), - the critical deformation (γ c), - the flow stress threshold (τ c), - the elastic force, - the critical stress (σ c), and - any combination thereof; the rheological parameter determined in the nonlinear region comprising at least σ c; and wherein the rheological parameter determined in the linear region is selected from: - the elastic modulus (G'), - the viscose modulus (G"), - the damping factor (tan δ), - the complex modulus (G*), - the plastic deformation (γ p), - the plastic stress (τ p), and - any combination thereof; - the elastic modulus (G'), - the viscose modulus (G"), - the damping factor (tan δ), - the complex modulus (G*), - the plastic deformation (γ p), - the plastic stress (τ p), and - any combination thereof; the rheological parameter determined in the linear region comprising at least G*.