Chronic obstructive pulmonary disease (COPD) induces changes in daily activities and mood. Health-related quality of life (HRQL) measures are of particular relevance in the management of such patients, but predictors of HRQL have rarely been investigated. The aim of this study was to seek factors predicting HRQL in severe COPD patients under long term oxygen therapy (LTOT). The pulmonary function parameters at the start of LTOT were studied as potential predictors of future HRQL. HRQL was assessed after an average of 40 months follow-up by the Duke Health Profile (Duke) and by the St. George Respiratory Questionnaire (SGRQ). Sixty-one patients (47 males and 14 females) with a mean age of 66 years were included in the study. Stepwise multiple regression analyses conducted in each HRQL dimension identified few significantly predictive factors. By the Duke, higher Self-esteem scores were associated with higher Pao2 (p < 0.01) and with older age (p < 0.05); higher Social Health scores were associated with older age (p < 0.005), and higher Pain scores were associated with a higher FEV1/FVC ratio (p < 0.05). By the SGRQ, the Activity score correlated with FEV1/FVC (p < 0.05). The proportion of the variance in each score accounted for by covariates in the model did not exceed 10%. No other significant regression models could be identified using the other HRQL dimensions. Our findings demonstrated weak relations between lung function at the start of LTOT and some dimensions of HRQL measured by the Duke and the SGRQ at the end of follow-up.