Gambling revenue at Plainridge Park Casino fell by about 4 percent in January, skidding to its lowest monthly level since December 2015.

Revenue dropped from $12.6 million in December to $12.1 million, according to figures released Wednesday by the state’s Gaming Commission. Revenue also fell slightly compared with last January, when the casino brought in $12.5 million.

Still, the Plainville slots parlor remains among the highest performing casinos in the country on a per-machine basis.

Plainridge is limited by law to 1,250 machines, about one-quarter the number at Connecticut rivals Foxwoods Resort Casino and Mohegan Sun. Plainridge, which opened in June 2015, is also prohibited from operating table games such as roulette and blackjack.

Casino managers expect slower business in the winter, when colder weather and the holiday season often interfere with gambling outings. But last January, the casino saw revenue jump 11 percent.

This January, however, was a different story. Overall wagers fell to $152 million, the lowest level in about a year.

The casino also reduced its payouts to gamblers, keeping nearly 8 cents per dollar last month. As recently as October, slot machines kept about 7 cents per dollar, giving gamblers substantially more wins.

For the month, the casino paid about $4.8 million in taxes and $1 million to support the struggling horse racing industry.

Plainridge opened in June 2015. Two much larger casinos, each with plans for at least 3,000 slot machines, are being built in Everett and Springfield.

Sean P. Murphy can be reached at smurphy@globe.com. Follow him on Twitter @spmurphyboston.