Biology of the Macaronesian endemic rockling Gaidropsarus guttatus was studied in the Azores. The overall sex ratio from the samples was highly in favour of females (1 : 6333). The growth parameters were L[SUB∝] = 24.23, k = 1.219 and t[SUB0] = -0.059. Fish matured at 15 cm L[SUBT] and the spawning season was strongly clustered in April.