We aimed to determine the ability of a set of physical fitness tests to discriminate between presence/absence of fibromyalgia (FM) and moderate/severe FM. The sample comprised 94 female FM patients (52 ± 8 years) and 66 healthy women (54 ± 6 years). We assessed physical fitness by means of the 30-s chair stand, handgrip strength, chair sit and reach, back scratch, blind flamingo, 8-feet up and go, and 6-min walking tests. Patients were classified as having moderate FM if the score in the Fibromyalgia Impact Questionnaire (FIQ) was <70 and as having severe FM if the FIQ was ≥70. FM patients and patients with severe FM performed worse in most of the fitness tests studied (P < 0.001). Except the back scratch test, all the tests were able to discriminate between presence and absence of FM [area under the curve (AUC) = 0.66 to 0.92; P ≤ 0.001], and four tests also discriminated FM severity (AUC = 0.62 to 0.66; P ≤ 0.05). The 30-s chair stand test showed the highest ability to discriminate FM presence and severity (AUC = 0.92, P < 0.001; and AUC = 0.66, P = 0.008, respectively), being the corresponding discriminating cutoffs 9 and 6 repetitions, respectively. Physical fitness in general, and particularly the 30-s chair stand test, is able to discriminate between women with FM from those without FM, as well as between those with moderate FM from their peers with severe FM.