Southend-on-Sea Council has prosecuted two landlords, both of which failed to act on formal repair notices.
The first case involved Habibur Rahman, whose property had widespread damp and mould, fall risks and several fire safety failings.
He ignored an earlier enforcement notice and was fined £440 with £2,200 in costs.
The second prosecution was for Madelaine Murphy of Leigh-on-Sea.
Her property also had damp and mould, as well as excess cold and dangerous fire hazards. After pleading guilty she received a £384 fine, plus £2,000 costs and a £154 victim surcharge
Cllr Martin Terry, cabinet member for community safety and regulatory services, told The Southend Echo: “More than a quarter of our residents live in privately rented housing, and their safety is our top priority.
“These prosecutions show the council will take tough action against landlords who break the law.”