Analyses of size at sexual maturity were undertaken on samples of Patagonian toothfish (Dissostichus eleginoides) caught in the commercial fishery within Subarea 48.3. The results for 1996 indicate that L_m50 occurs at 78.5 cm total length for male and 98.2 cm for female fish. In 1997 the results for male fish were essentially the same. For female fish there is evidence that in 1997 a significant proportion, 25 to 43%, of sexually mature fish were not coming into spawning condition. This introduces a bias leading to the overestimation L_m50 of  calculated by conventional methods. Further analysis allowing for this bias indicates that L_m50 for female fish in 1997 was no different to that for 1996. The implications of this phenomenon are discussed.