Chronic heart failure (CHF) and chronic obstructive pulmonary disease (COPD) are two clinical conditions often associated with cognitive dysfunctions, psychological distress, poor quality of life (QoL), and functional worsening. In addition, since patients suffering from these conditions are often older adults, frailty syndrome represents a further and important issue to be investigated. The present preliminary study aimed to perform a multidimensional assessment of CHF and/or COPD older patients (age ≥65) undergoing cardiac or pulmonary rehabilitation. The characteristics of the included patients (30 CHF and 30 COPD) resulted almost similar, except for the COPD patients' longer duration of illness and better performances in Addenbrooke's cognitive examination III subtests and short physical performance battery (SPPB). No significant differences were found in the frailty evaluation, but a consistent number of patients resulted to be frail (CHF=36.7% vs COPD=26.6%). After the rehabilitation program, a significant improvement was found in the whole sample concerning the executive functions (14.34±2.49 vs 15.62±2.22, p=0.001), quality of life (58.77±18.87 vs 65.82±18.45, p=0.003), depressive and anxious symptoms (6.27±4.21 vs 3.77±3.39, p=0.001 and 5.17±3.40 vs 3.38±3.21, p=0.001), frailty status [4.00 (3.00,5.00) vs 3.00 (3.00,5.00) p=0.035] and functional exercise abilities [SPPB, 7.40±3.10 vs 9.51±3.67, p=0.0002; timed up and go test, 14.62±4.90 vs 11.97±4.51, p<0.0001; 6-minute walking test, 353.85±127.62 vs 392.59±123.14, p=0.0002]. Preliminary results showed a substantial homogeneity of CHF and COPD older patients' cognitive, psychosocial, frailty, and functional characteristics. Nevertheless, the specific rehabilitation intervention appears promising in both clinical populations. This trial has been registered with the ClinicalTrials.gov, NCT05230927 registration number (clinicaltrials.gov/ct2/show/NCT05230927).