A sample of 17,683 individuals of Dosidicus gigas was collected between 1991 and 1994 from Japanese and Korean fishery boats by on-board Peruvian observers. On the basis of a modification of the Nesis (1970) macroscopic scale, four stages of maturity for females and males were assessed. The mean mantle length at first maturity was 32 cm for females and 28 cm for males. For the period 1991 to 1994, the spawning peaks were identified using three different methods; the spawning progression (variation of the III stage over time), variation of the nidamental gland index ((LNG/ML)×100) and the gonadosomatic index (Gonad weight × 103/ML3). Spawning extends throughout the year, but the most important spawning peak occurs during October to January, without variation between the years of study. Secondary peaks were identified during July and August. The variation in nidamental gland length in relation to mantle length provides an acceptable index to indicate when spawning occurs.