Roosting, nesting and breeding behaviour of rose-ringed parakeet was observed at four different locations in campus of the University of Karachi. Number, species, trunk diameter and location of dominant trees, and the number of parakeets leaving and returning to roosts at all locations were observed. Overall 103 nest cavities (average 9.92 ± 1.89 per location) were observed. Out of which 36 active nest cavities (average 2.77 ± 0.96 per location) were selected to observe breeding behaviour of the parakeets. Significant relationship was observed between the number of nests and the tree diameter. Number of eggs per nest ranged between 2 to 5 with an incubation period ranging between 19 to 25 days. Tree specie, trunk diameter, height of nest from the ground and breeding success (number of fledging chicks in nest) were observed. Fledging period of the chicks was observed to be 6 to 7 weeks. A perfect negative relationship was observed between the height and the number of nests. A negative relationship was observed between the nest height and fledging chicks.