A member of radical feminist group Femen staged a naked protest outside the Polish embassy in Kiev on Monday against a near-total ban on abortion in the EU country.
The English words "My body is my choice" were scrawled on her torso. She held coat hangers in her mouth, a protest symbol representing illegal abortions.
"Sisters to arms!" the woman chanted in Polish before being quickly arrested by police.
Later in the day several dozen activists gathered near the embassy for another demonstration in support of Polish women.
One of the women held a placard saying: "When the government decides to ban safe abortions women may decide to abort the government."
Last week Poland's constitutional court ruled that an existing law allowing the abortion of malformed foetuses was "incompatible" with the constitution.
The ruling has sparked protests against a near-total ban on abortion in a country that already has some of the EU's most stringent restrictions.
According to media reports, Ukraine's much more liberal policies make it one of the destinations for Polish women seeking abortions.
From now on, abortions in Poland will only be allowed in instances of rape or incest, or if there is a threat to the mother's life.