The objective of this study was to investigate the possible effects of the daily stress experienced during a six-month period on the cognitive functioning of patients with systemic lupus erythematosus (SLE). For this purpose, we evaluated the daily stress of 21 patients with lupus every day for six months. Later, we carried out a neuropsychological exam that included an evaluation of attention and memory. At the same time, scores on depression and anxiety were recorded with the objective of controlling other emotional variables that might be influencing these cognitive processes. The results show that daily stress was able to predict the scores on the neuropsychological variables studied. Specifically, the daily stress experienced in the previous six months is the variable with the greatest explanatory-predictive power on the scores for delayed recall visual memory, visual fluency and attention speed. This relationship proved to be negative in all three cases (R2 corr = 0.290; t = -2.712, P < 0.014); (R2 corr = 0.318; t = -2.818, P < 0.012); (R2 corr = 0.319; t = -2.906, P < 0.009), which means that the greater the daily stress, the lower the score on visual memory, fluency and total attention speed. We can state that daily stress is related to impairments in visual memory, fluency and attention in patients with SLE. This effect was not found with other emotional variables, such as depression and anxiety.