There is no direct statutory planning enforcement mechanism for land without a history of Interim Development Permission Area Plans or Development Permission Area Plans in Hong Kong. Indirect enforcement of planning conditions is largely conducted by the Buildings Department upon building approval and by the Lands Department if the conditions are incorporated into the lease. The extent to which planning conditions are incorporated into leases is largely unknown, impacting the effect of this indirect contractual enforcement. The extent and probabilities of the incorporation of planning conditions in Comprehensive Development Area zones into leases are investigated. A total of 339 planning conditions on thirty-eight sites were identified but some were excluded from the study, leaving 188 for analysis. These conditions were categorised into eight types and tested with a probit model. It was found that three categories of planning conditions (access improvement, footbridges, lay-bys, and public vehicle parks; social facilities such as open space, day nursery, or kindergarten; water supply, draining, sewage) had the highest percentages of incorporation into leases, while the percentage for a fourth category (layout, landscape, car park plan) was not very high but still significantly higher than the other four categories.