Ramdin added 44 runs for the last wicket with Corey Collymore (eight not out) as the tourists recovered from 216-9 to 260 all out at the National Stadium. They trail Pakistan's first-innings score of 304 by 44 runs.
Ramdin was the last man out after he failed to make the crease at the non-striker's end while attempting a second run. He hit seven boundaries.
Despite dismissing the resolute West Indian opener Daren Ganga (81) early in the day, Pakistan wicket-keeper Kamran Akmal dropped three chances to let the tourists' tail add 69 runs after they resumed at 191-6.
Ramdin held on after Ganga fell in the fifth over of the day. Ganga played a casual shot to an incoming delivery from Abdul Razzaq and was caught by Akmal behind the wicket.
Ganga, who was 77 overnight, hit nine boundaries during his 304-minute knock.
Pakistan took the second new ball with the West Indies on 213-8 and fast bowler Umar Gul bowled Daren Powell with the second delivery for one to finish with 4-79.
Gul had jolted the West Indies with three wickets off just ten balls on Tuesday, including the prized wicket of Brian Lara for a second ball duck.
Ramdin, dropped on five by Akmal off leg-spinner Danish Kaneria, took full advantage of the chance and hit Gul for three boundaries before reaching his fourth Test half-century.
Kaneria finished with 3-62.
Pakistan 304 vs West Indies 260 all out (Daren Ganga 81, Denesh Ramdin 50, Chris Gayle 40, Chanderpaul 36; Umar Gul 4 for 79, Danish Kaneria 3 for 62)