The constituents of nigella sativa modulate the immune system. The aim of the present work was to study the effectiveness of nigella sativa oil in RA patients. Data from 40 female RA patients diagnosed according to the 2010 ACR/EULAR were analysed and discussed. The patients took two placebo (starch filled) capsules daily for 1?month. This was followed by a month of nigella sativa oil capsules 500?mg twice/day. The disease activity score (DAS-28) significantly decreased after receiving the nigella sativa capsules (4.55???0.82) compared with before and after placebo (4.98???0.79 and 4.99???0.72, respectively) (p?=?0.017). Similarly, the number of swollen joints and the duration of morning stiffness improved. A marked improvement in the disease activity was shown by both the ACR20 and EULAR response criteria in 42.5% and 30% of the patients, respectively, after intake of Nigella. Supplementation with nigella sativa during DMARD therapy in RA may be considered an affordable potential adjuvant biological therapy. Copyright ? 2011 John Wiley & Sons, Ltd.