In the treatment of patients with cardiorespiratory pathology, it is often necessary to simultaneously administer drugs that affect β-adrenergic receptors: β₁-adrenoblockers and β₂-agonists. β₁-blockers can trigger a bronchospasm in patients with bronchoobstructive diseases, therefore, practitioners often decide not to prescribe them. This work aimed to evaluate functional parameters of patients with cardiovascular and bronchoobstructive diseases in the context of different sequences of administration of selective β₁-blockers (bisoprolol) and long-acting β₂-agonists (formoterol). This prospective, single-center 2-week pilot study involved 30 individuals suffering the aforementioned diseases. Using the envelopes method, we divided the patients into two groups of 15 people each. First group started therapy with a long-acting β₂-agonist, second group — with a selective β₁-adrenoblocker. While taking the β₁-adrenoblocker, patients underwent a four-hour spirometric test enabling assessment of the external respiration function parameters. The tests and assessments have shown that the value of FEV1 went down in 33.3% of those who started therapy with a selective β₁-adrenoblocker (bisoprolol 2.5 mg), and in the group that first took a long-acting β₂-agonist for a week and then added bisoprolol 2.5 mg to the regimen the said value dropped in 7% of patients only. Thus, preceding long-acting β₂-agonists, formoterol in particular, reduced the risk of bronchospastic incidents triggered by selective β₁-adrenoblocker (bisoprolol) in patients with cardiorespiratory pathology.