We studied 94 patients diagnosed of sarcoidosis in order to establish the incidence of erythema nodosum (EN), in the course of sarcoidosis, in our setting and to check if it induces different clinical and analytical characteristics in patients. 37 patients (39%) showed EN with a mean age of 41 +/- 1.62 years and with a marked female predominance (81%). Its presence was associated with a higher frequency of general symptoms (p less than 0.01), articular manifestations (p less than 0.001), specially in knees and ankles (p less than 0.01), subacute evolution (p less than 0.001), raise in GSR and of alpha-one-globulin (p less than 0.01) and hypoalbuminemia (p less than 0.05). On the other hand, those patients without EN showed higher frequency of dermal lesions different from EN (p less than 0.001) and the articular manifestations were localized preferentially in knees and proximal interphalangeal articulations of hands (p less than 0.05). We underline the high incidence of EN in sarcoidosis in our setting, which originates a more benign clinical type with a more favorable prognostic, embedded in the course of sarcoidosis, to which EN would transfer its clinical, analytical and immunopathogenic characteristics.