In this paper, it is investigated whether an implicit evaluative-negative attitude towards back-stressing activities exists in pain-free subjects and in chronic low back pain patients. Using an affective priming task, it was investigated whether pictures of threatening back-stressing movements (primes) facilitate (respectively, slow down) the categorisation of subsequent evaluative-negative (evaluative-positive) words (targets). In study 1 using 20 pain-free subjects, the affective priming effect indicated evidence for an implicit negative attitude towards pictures of back-stressing activities. In study 2 using 30 low back pain patients, a reverse priming effect was found. In line with previous research, it is argued that this reverse priming effect is owing to the evaluative extremity of the primes: patients recognize the possibility that extreme primes will interfere with the categorisation of the targets and overcompensate for this possible effect. The implications for the prevention of negative attitudes towards back-stressing activities in non-clinical and clinical samples are discussed.