Greetings, I was able to make a small change to axes.py which augments errorbar() with a keyword, 'ealpha' (similar to 'ecolor'), which controls the alpha blending of the error bar lines. The motivation was to make overlapping error bars of different color slightly less confusing (or at least more interesting). It's up to the user to resist the temptation to utilize it for "error reduction." ;) Patch attached, use ad lib. Mike