A method of treating a human subject which is effected by inhalation of gaseous nitric oxide, the method comprising a first treatment period comprising administering gNO by inhalation over a period of about at least 5 days, wherein the first treatment period is followed by a second treatment period comprising administering gNO by inhalation over a period of at least 3 months. The method can be utilized for treating a human subject suffering from, or prone to suffer from, a disease or disorder that is manifested in the respiratory tract, or from a disease or disorder that can be treated via the respiratory tract. The disclosed method can be effected while monitoring one or more of on-site and off-site parameters such as vital signs, methemoglobin levels, pulmonary function parameters, blood chemistry and hematological parameters, blood coagulation parameters, inflammatory marker levels, liver and kidney function parameters and vascular endothelial activation parameters, such that no substantial deviation from a baseline in seen in one or more of the monitored parameters.
