With 65 percent of today's vote counted, the People's Democratic Party of Tajikistan (PDPT) chaired by President Emomali Rakhmon was on course to take the vast majority of the legislature's 63 seats.
But the opposition Islamic Renaissance Party of Tajikistan (IRPT) -- the only registered faith-based party in ex-Soviet Central Asia -- failed to win a single seat for the first time since 1999.
Its chairman, Muhiddin Kabiri, said the party refused to accept results that "did not correspond with reality".
Another opposition group, the Social Democratic Party of Tajikistan, critical of the Rakhmon government, failed to win any seats, as did the Communist Party.
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Three other parties that made it into parliament -- the Agrarian Party, the Party of Economic Reforms of Tajikistan and the Socialist Party of Tajikistan -- are broadly viewed as pro-government.
The IRPT complained of government harassment during the campaign and a report by foreign election observers painted a damning picture.
The OSCE Parliamentary Assembly added: "The imbalanced coverage by state media, negative reporting on the opposition Islamic Revival Party of Tajikistan, and the absence of genuine political debate considerably limited the opportunity for voters to make an informed choice.