Women directed 16 per cent of the nearly 4,000 episodes that aired last season, a year-to-year increase of 2 per cent, the guild found.
Minorities, both male and female, directed 18 percent of episodes, a 1 percent dip, according to an analysis of episodes from nearly 280 broadcast, cable and online series from the 2014-15 season.
Both the TV and movie industries have long been under scrutiny for a lack of opportunity for women and minorities, with studies by entertainment unions and others finding that the preference for hiring white men is deeply entrenched.
But the video-on-demand services that are contributing to the explosion of choices are also abetting the status quo, the guild said.
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Netflix, Amazon and PlayStation fielded series that appeared on the guild's "Worst" list of 61 shows that hired women or minority directors for fewer than 15 percent of episodes.
Some didn't hire any women or minorities for the season studied, the guild said, including Netflix's "Marco Polo" and PlayStation's "Powers."
"With so many more episodes and work opportunities, employers should seize the opportunity for diversity with their choices, especially when it comes to first-time episodic directors."
Of the 128 first-time TV directors hired in the 2014-15 season, 84 per cent were male, up from 80 per cent in the previous season, hiring that has a "significant impact" on the hiring pool over time, the guild said.
While there was a 5 per cent increase in the number of episodes directed by minorities, to 694 from 660 in 2013-14, that represents half the percentage increase in total episodes.