Objectives: This descriptive study aims to determine the relationship between alexithymia and social support in patients with hypertension and asthma. Methods: The study population consisted of patients admitted to the Cardiology and Chest Diseases polyclinics in two hospitals in Erzurum (Turkey) between April, 1 and May, 15 2011 and diagnosed with hypertension and asthma. The study sampling consisted of 191 patients with hypertension and 150 patients with asthma (341 patients) who agreed to participate in the study. Data were collected using a personal information form, the Toronto Alexithymia Scale (TAS-20), and the Perceived Social Support from Family and Friends Scale (PSS-FA and PSS-FR). Data were analyzed using percentage distributions, means, t test, and the Pearson correlation test. Results: Of the patients with hypertension, 38.2%, and of the patients with asthma, 36% were found to be alexithymic. The perceived social support from friends scores of the alexithymic patients with hypertension (p=0.004), and from family of the alexithymic patients with asthma (p=0.002) were lower than those of non-alexithymic patients, and the difference was significant. A significant difference was found between the perceived social support from friends and alexithymia levels of the patients with hypertension and the perceived social support from family and alexithymia levels of the patients with asthma (p< 0.001). Lower alexithymia score averages were found to be related to lower perceived social support. The total score average of the patients with hypertension on the alexithymia scale was found to be 59.72 +/- 7.56, and their score average on the difficulty in recognizing emotions subscale was found to be 18.4 +/- 5.19. The total score average of the patients with asthma on the alexithymia scale was found to be 57.00 +/- 7.43, and their score average on the difficulty in recognizing emotions subscale was found to be 15.28 +/- 4.40. The total score average on the alexithymia scale and on the difficulty in recognizing the emotions subscale of the patients with hypertension were found to be higher than those of the patients with asthma, and the difference was statistically significant (p=0.001). The perceived social support from family of the patients with hypertension (14.26 +/- 3.65) was found to be higher than that of the patients with asthma (11.83 +/- 3.75), and the difference was significant. Conclusion: It can be concluded that the perceived social support of the alexithymic patients is lower. Patients with an alexithymic chronic disease may need more help, especially from health professionals, in activating social support systems. It is important for health professionals to know the alexithymic patients. Based on these results, it is recommended that healthcare personnel be informed about alexithymia, and protective social support systems be activated in mental problems such as alexithymia that emerge in chronic diseases.