We studied the association between alexithymia (20-item Toronto Alexithymia Scale, TAS-20) and obesity, and also assessed the construct validity of the TAS-20 in terms of personality dimensions in obese patients. The TAS-20 and its subscales were analysed for their correlations with the NEO Personality Inventory - Revised (NEO PI-R) in an obese sample of 259 patients. Obesity was associated with higher scores on the TAS-20 than a Swedish reference sample. Obese men furthermore scored higher on Externally Oriented Thinking than the obese women. TAS-20 scores correlated with elevated Neuroticism and lower levels of Extraversion and Openness, in agreement with most previous research, but also somewhat unexpectedly with lower Conscientiousness and for women also with lower Agreeableness. The TAS-20 subscales showed divergent associations with personality variables, largely in accordance with previous findings. The associations were more prominent for the women, and some gender-specific patterns not previously reported were also revealed.