25-year-old Prachi was rushed to a private hospital on Tuesday night and from there she was referred to a hospital in Delhi, where she breathed her last, police said.
On the complaint of her father, police have registered a case against Prachi's husband Manish, her father-in-law Suresh Chand Tyagi, her mother-in-law and sister-in-law.
Gajraj Singh, the father of Prachi and a resident of Paschim Vihar area of Delhi, said in the complaint that his daughter got married to Manish about a year ago and her in-laws were constantly harassing her for dowry.
Singh alleged that on Tuesday night Prachi's in-laws administered her poison.
A probe is on and the accused will be arrested soon, said Ran Vijay Singh, Circle Officer of Sihani Gate police station.