This study was done to verify validity of nursing diagnoses related to difficulty in respiratory function. First, content validity was examined by an expert group considering the etiology and the signs / symptoms of three nursing diagnoses - ineffective airway clearance, ineffective breathing pattern, impaired gas exchange. Second, clinical validity was examined by comparing the frequencies of the etiologies and signs / symptoms of the three nursing diagnoses in clinical case studies with the results of the content validity. This study was a descriptive study. The sample consisted of 23 experts (professors, head nurses and clinical instructors) who had had a variety of experiences using nursing diagnoses in clinical practice, and 102 case reports done by senior student nurses of the college of nursing of Y-university. These reports were part of their clinical practice in the ICU. The instrument used for this study was a checklist for etiologies and signs and symptoms based on the literature, Doenges and Moorhouse (1988), Kim, McFarland, McLane (1991), Lee Won Hee et al. (1987), Kim Cho Ja et at. (1988). The data was collected over four month period from May 1992 to Aug. 1992. Data were analyzed using frequencies done with the SPSS / PC＋ package. The results of this study are summarized as follows : 1. General Characteristics of the Expert Group A bachelor degree was held by 43.5% and a master or doctoral degree by 56.5% of the expert group. The average age of the expert group was 35.3 years. Their average clinical experience was 9.3 years and their average experience in clinical practice was 5.9 years. The general characteristics of the patients showed that there were more women than men, that the age range was from 1 to over 80. Most of their medical diagnoses were diagnoses related to the respiratory. system, circulation or neurologic system, and 50% or more of them had a ventilator with intubation or a tracheostomy. The number of cases for each nursing diagnoses was : · Ineffective airway clearance, 92 cases. · Ineffective breathing pattern, 18 cases. · Impaired gas exchange, 22 cases. 2. The opinion of the expert group as to the classification of the etiology, and signs and symptoms of the three nursing diagnoses was as follows : · In 31.8% of the cases the classification of etiology was clear. · In 22.7%, the classification of signs and symptoms was clear. · In 17.4%, the classification of nursing interventions was clear. 3. In the expert group 80% or mere agreed to ‘dysp-nea’as a common sign and symptom of the three nursing diagnoses. The distinguishing signs and symptoms of (Ineffective airway clearance) were ‘sputum’, ‘cough’, ‘abnormal respiratory sounds : rales’. The distinguishing sings and symptoms of (Ineffective breathing pattern) were ‘tachypnea’, ‘use of accessory muscle of respiration’, ‘orthopnea’ and for (Impaired gas exchange) it was ‘abnormal arterial blood gas’, 4. The distribution of etiology, and signs and symptoms of the three nursing diagnoses was as follows : · There was a high frequency of ‘increased secretion from the bronchus and trachea’ in both the expert group and the case reports as the etiology of ineffective airway clearance. · For the etiologies for ineffective breathing pat-tern, ‘rain’, ‘anxiety’, ‘fear’, ‘obstructions of the tract, ca and bronchus’ had a high ratio in the ex-pert group and ‘decreased expansion of lung’ in the case reports. · For the etiologies for impaired gas exchanges, ‘altered oxygen -carrying capacity of the blood’ and ‘excess accumulation of interstitial fluid in lung’ had a high ratio in the expert group and ‘altered oxygen supply’ in the case reports. · For signs and symptoms for ineffective airway clearance, ‘dyspnea’, ‘altered amount and character of sputum’ were included by 100% of the expert group. ‘Abnormal respiratory. sound(rate, rhonchi)’ were included by a high ratio of the expert group. · For the signs and symptoms for ineffective breathing pattern. ‘dyspnea’, ‘shortness of breath’ were included by 100% of the expert group. In the case reports, ‘dyspnea’ and ‘tachypnea’ were reported as signs and symptoms. · For the sign and symptoms for impaired gas exchange, ‘hypoxia’ and ‘cyanosis’ had a high ratio in the expert group. In the case report, ‘hypercapnia’, ‘hypoxia’ and ‘inability to remove secretions’ were reported as signs and symptoms. In summary, the similarity of the etiologies and signs and symptoms of the three nursing diagnoses related to difficulty in respiratory function makes it difficult to distinguish among them But the clinical validity of three nursing diagnoses was established through this study, and at last one sign and symp-tom was defined for each diagnosis.