Pulmonary hypertension (PH) was found to be the primary cause of death in mixed connective tissue disease (MCTD). This led to investigation of the prevalence of PH in other connective tissue diseases (CTD). In 1998, the Ministry of Health and Welfare's MCTD Research Committee revealed complication of PH diagnosed by physicians in 5.02% MCTD patients, 0.90% systemic lupus erythematosus patients, 2.64% systemic sclerosis patients, and 0.56% polymyositis/dermatomyositis patients. These results have been supported by a similar survey performed in North America. As quite a few rheumatologists find right heart catheterization difficult to perform, doppler echocardiography is frequently used for screening and diagnosing PH. The MCTD Research Committee set the revised criteria for MCTD-PH, in which the threshold of estimated pulmonary arterial systolic pressure value for diagnosis of pulmonary arterial hypertension (PAH) is set at 36 mmHg, as proposed by the European Society of Cardiology. Right heart catheterization is strongly recommended for commencing the treatment. Since PH due to thromboembolism can potentially be cured surgically, lung perfusion scintigraphy should be performed for all patients diagnosed with PH. Most CTD-PH are PAH, and since idiopathic PAH (IPAH) patients sometimes have immune disorders, treatment for IPAH may be applicable to CTD-PH. The greatest difference between the treatment strategy for CTD-PH and IPAH is the usage of corticosteroids and other immunosuppressants. The MCTD Research Committee updated its therapeutic guidelines for MCTD-PH in 2011. Validation of these guidelines is also needed.